SEARCH · Search PubMed

Results for “Protamines”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed1993

Characterization of a marsupial sperm protamine gene and its transcripts from the North American opossum (Didelphis marsupialis).

A synthetic oligonucleotide primer, designed from marsupial protamine protein-sequence data [Balhorn, R., Corzett, M., Matrimas, J. A., Cummins, J. & Faden, B. (1989) Analysis of protamines isolated from two marsupials, the ring-tailed wallaby and gray short-tailed opossum, J. Cell. Biol. 107] was used to amplify, via the polymerase chain reaction, protamine sequences from a North American opossum (Didelphis marsupialis) cDNA. Using the amplified sequences as probes, several protamine cDNA clones were isolated. The protein sequence, predicted from the cDNA sequences, consisted of 57 amino acids, contained a large number of arginine residues and exhibited the sequence ARYR at its amino terminus, which is conserved in avian and most eutherian mammal protamines. Like the true protamines of trout and chicken, the opossum protamine lacked cysteine residues, distinguishing it from placental mammalian protamine 1 (P1 or stable) protamines. Examination of the protamine gene, isolated by polymerase-chain-reaction amplification of genomic DNA, revealed the presence of an intron dividing the protamine-coding region, a common characteristic of all mammalian P1 genes. In addition, extensive sequence identity in the 5' and 3' flanking regions between mouse and opossum sequences classify the marsupial protamine as being closely related to placental mammal P1. Protamine transcripts, in both birds and mammals, are present in two size classes, differing by the length of their poly(A) tails (either short or long). Examination of opossum protamine transcripts by Northern hybridization revealed four distinct mRNA species in the total RNA fraction, two of which were enriched in the poly(A)-rich fraction. Northern-blot analysis, using an intron-specific probe, revealed the presence of intron sequences in two of the four protamine transcripts. If expressed, the corresponding protein from intron-containing transcripts would differ from spliced transcripts by length (49 versus 57 amino acids) and would contain a cysteine residue.

Amino Acid Sequence↗

PubMed1993

Effects of heparin on the vasodilator action of protamine in the rabbit mesenteric artery.

1. The effects of protamine on the rabbit isolated small mesenteric artery were investigated both in the presence and in the absence of heparin, by the isometric tension-recording method. 2. The dissociation constant for the binding of heparin to protamine has never been previously reported, so in order to minimize the effects of protamine, known to have a vasodilator action, and to examine only the effects of a heparin-protamine complex, the experiments with heparin were performed in the presence of high concentrations of heparin (21-700 u ml-1), concentrations at which heparin itself does not affect the vascular tone. 3. Protamine (15-500 micrograms ml-1), in the absence of heparin, was found to inhibit (P < 0.05) noradrenaline (1 microM)-induced contractions both in endothelium-intact and in endothelium-denuded tissues. 4. Such vasodilator action of protamine in either endothelium-intact or -denuded tissues continued, even in the presence of excess heparin at a heparin/protamine (H/P) ratio of 1.4 u micrograms -1, but was almost completely blocked in the presence of a much greater excess of heparin (H/P ratio > or = 4.7 u micrograms -1): heparin was present both before and during the application of protamine. 5. The vasodilator action of protamine in the absence of heparin was prolonged both in the endothelium-intact and -denuded tissues after protamine had been washed out from the bath with Krebs solution. Although this washing out with a Krebs solution containing excess heparin (4.7 u ml-1) readily reversed such prolonged vasodilator action of protamine both in the endothelium-denuded strips and in the endothelium-intact strips which had been pretreated with inhibitors of the endothelium-derived relaxing factor (EDRF) pathway, it did not affect the prolonged vasodilator action of protamine in the endothelium-intact strips which received no pharmacological intervention.6. These results suggest that: (1) only protamine, not a heparin-protamine complex, exerts vasodilator action in vitro; (2) the vasodilator action of protamine presumably has an EDRF-mediated component;and (3) protamine probably exerts its direct vasodilator action without entering the smooth muscle cell.

Animals↗

PubMed2006

Protamine levels vary between individual sperm cells of infertile human males and correlate with viability and DNA integrity.

Sperm protamine deficiency has been associated with human male infertility. However, most studies have adopted a global approach to assessing sperm protamine levels. Thus, it is not known whether sperm cells from individual human males possess variations in protamine protein content. The objectives of this study were to evaluate variations in protamine-1 (P1) and protamine-2 (P2) content between individual sperm cells of fertile and infertile men and to correlate DNA integrity and sperm cell viability with protamine levels in individual sperm cells. The semen samples of fertile and infertile men were evaluated globally for protamine protein content using nuclear protein extraction, gel electrophoresis, and densitometry analysis. Individual sperm cell P1 and P2 levels were assessed using immunofluorescence microscopy in conjunction with automated image analysis. The terminal transferase dUTP nick end labeling (TUNEL) assay was performed simultaneously with protamine immunostaining to assess the relationship between protamine levels and DNA integrity in individual spermatozoa. Additionally, the relationship between sperm cell viability and protamine levels was assessed via viability staining concomitant with protamine staining. The protamine fluorescence data demonstrate significant variations in protamine content within individual sperm cells of human males. Overall population-based measures of DNA integrity and sperm cell viability correlate significantly with population-based measurements of protamine levels. The data also demonstrate individual sperm cells displaying the lowest protamine levels display diminished viability and increased sperm cell susceptibility to DNA damage.

Cell Survival↗

PubMed2001

Automated protamine dose assay in heparin reversal management after cardiopulmonary by pass.

BACKGROUND: To evaluate the impact of automated Protamine Dose Assay (PDA) performed with Hemochron 8000 (International Technodyne Company, Edison, NJ) on the management of heparin reversal after cardiopulmonary bypass (CPB). PDA was compared with empirical protamine to heparin ratio with regard to calculation of the protamine dose, and the sensitivity of PDA and ACT to residual circulating heparin after protamine administration was investigated too. METHODS DESIGN: prospective and randomized study. SETTING: cardiac surgical center of a General Hospital. PARTICIPANTS: 50 patients undergoing elective cardiac surgery with CPB. INTERVENTIONS: after CPB patients randomly received protamine according to our standard empirical ratio of 1 mg. protamine/100 U. heparin (group S, 24 patients), or to PDA result (group T, 26 patients) based on protamine titration method of determining circulating heparin. After protamine administration ACT and PDA were performed to assess heparin reversal and detect residual circulating heparin. Based on the PDA result, additional protamine was administered in both groups when required. MEASUREMENTS: in both groups basal and post-heparin ACT values, protamine doses, ACT and PDA after protamine administration were measured. RESULTS: The protamine dose was significantly lower (30%) in patients treated according to PDA. In 20% of patients showing normal ACT PDA revealed still circulating heparin, and additional protamine was required. In all other cases ACT and PDA both confirmed heparin reversal. CONCLUSIONS: PDA allowed us to administer a significantly lower amount of protamine. This can reduce incidence of adverse effects of over- and under-infusion of protamine. PDA also proved to be more sensitive than ACT in detecting residual circulating heparin after protamine administration.

Anticoagulants↗

PubMed1994

Effects of protamine on myocyte contractile function and beta-adrenergic responsiveness.

The use of protamine sulfate in patients has been associated with severe circulatory collapse and myocardial failure. However, the exact mechanisms responsible for these reactions to protamine remain unclear. Accordingly, we examined the effect of protamine on isolated myocyte contractile function. Indexes of isolated myocyte contractile function, percent shortening, and velocity of shortening were examined using videomicroscopy. Porcine cardiocytes (n = 75) were studied at baseline and in the presence of 80 micrograms/mL protamine. In addition, myocyte function was examined sequentially, first during treatment with 8 IU/mL heparin and then after the addition of a protamine dose sufficient to completely bind the heparin. The binding of heparin and protamine resulted in the formation of a heparin-protamine complex. The protamine concentration of 80 micrograms/mL is approximately equal to the serum concentration of protamine obtained in patients when administered in a dose of 5 mg/kg. In the presence of 80 micrograms/mL protamine, both percent shortening and velocity of shortening fell by more than 32% from baseline values (p < 0.05). The presence of either heparin alone or the heparin-protamine complex resulted in no change in baseline myocyte contractile measurements. Furthermore, to examine the effect of protamine on myocyte beta-adrenergic responsiveness a second series of experiments were performed. Myocyte contractile function was measured when 25 nmol/L isoproterenol was added to each of the protocols above. The presence of 80 micrograms/mL protamine resulted in a significant blunting of myocyte beta-adrenergic responsiveness. The presence of either heparin alone or the heparin-protamine complex resulted in no change in myocyte beta-adrenergic responsiveness.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1999

Isoflurane and sodium nitroprusside reduce the depressant effects of protamine sulfate on isolated ischemic rat hearts.

UNLABELLED: The administration of protamine sulfate (protamine) to reverse the action of heparin is associated with adverse reactions. We studied the effects of protamine and isoflurane on isolated, perfused rat hearts previously subjected to cardioplegic ischemia. Hearts were perfused with oxygenated Krebs-Henseleit (KH) solution for 30 min, then subjected to cardioplegic ischemia for 30 min (KCl 16 mEq/L at 31 degrees C) and 5 min reperfusion. Drug exposure lasted 15 min, and the recovery period was 60 min. Test groups were control, protamine (10 microg/mL), isoflurane (1.5%), protamine +/- isoflurane, sodium nitroprusside (SNP) (2.5 ng/mL), and SNP +/- protamine. Left ventricular developed pressure (LVP), coronary flow, and myocardial oxygen consumption were depressed by protamine to 30% +/- 4%, 47% +/- 4%, and 39% +/- 4% of baseline (P < 0.001 versus control), respectively. Isoflurane and SNP afforded partial protection from the effects of protamine: LVP was 57% +/- 5% and 51% +/- 3% of baseline, respectively (P < 0.05 versus protamine alone and control); coronary flow was 70% +/- 6% and 97% +/- 12% of baseline, respectively (P < 0.05 versus protamine alone; P < 0.05 for isoflurane versus control); and O2 consumption was 69% +/- 6% and 88% +/- 15% of baseline, respectively (P < 0.05 versus protamine; P < 0.05 for isoflurane versus control). In this model, protamine-induced myocardial depression and coronary vasoconstriction were less pronounced in the presence of either isoflurane or SNP. IMPLICATIONS: We examined the interactions of isoflurane, sodium nitroprusside, and protamine in a rat heart model and found that both isoflurane and sodium nitroprusside partially protect the heart from the depressant effects of protamine. This finding is significant, as these drugs are often used in heart surgery.

Anesthetics, Inhalation↗

PubMed1992

Immunological evidence for a P2 protamine precursor in mature rat sperm.

High molecular weight proteins in Rattus norvegicus that are immunoreactive with an anti-protamine 2 specific antibody but not with an anti-protamine 1 specific antibody are described. These proteins were detected by coupling high-performance liquid chromatography (HPLC) with an enzyme-linked immunosorbent assay (ELISA). Briefly, following HPLC separation of rat sperm nuclear proteins, the HPLC fractions were probed with the antibodies. We estimate that the antibody probes are 100-1000 times more sensitive than UV absorbance measurements. Immunoblot analysis following acid-urea electrophoretic separation of rat sperm nuclear proteins, and of the HPLC fractions, also detected putative protamine 2 precursor proteins. The proteins reactive with the anti-protamine 2 antibody are most likely not mature protamine 2, since they were detected in a region of the chromatogram where we would not expect protamine 2 to migrate based on the chromatographic locations of human and mouse protamine 2. Likewise, the immunoblotting experiments demonstrated that the anti-protamine 2 antibody recognized proteins with slower electrophoretic mobilities than would be expected for a mature protamine 2. An anti-protamine 1 monoclonal antibody, Hup1N, that binds rat protamine 1 is also described. Hup1N allowed for identification of the HPLC fractions that contained rat protamine 1. Finally, we demonstrated that Hup1N binds protamine 1 from a large number of species, suggesting a conserved epitope for Hup1N.

Animals↗

PubMed1995

Differential effects of protamine sulfate on myocyte contractile function with left ventricular failure.

OBJECTIVES: This project tested two fundamental hypotheses: 1) Protamine sulfate has a direct and negative effect on myocyte contractile processes; 2) the negative effects of protamine on myocyte contractility will be enhanced in the setting of chronic left ventricular dysfunction. BACKGROUND: An increasing number of patients undergoing cardiac and vascular surgical procedures have underlying chronic left ventricular dysfunction. Protamine sulfate is commonly required during these surgical procedures but has been associated with left ventricular dysfunction. However, it is not known whether protamine may have a direct and selective effect on myocyte contractility in the setting of chronic left ventricular dysfunction. METHODS: This study examined the direct effects of protamine on isolated myocyte contractile function in 10 control pigs and 10 pigs with dilated cardiomyopathy induced by supraventricular tachycardia (rapid atrial pacing at 240 beats/min for 3 weeks). Myocyte contractile function was measured by videomicroscopy at baseline and with 10, 20, 40 or 80 micrograms/ml of protamine. In a second series of experiments, myocytes were preincubated with protamine and then stimulated with the beta-adrenergic agonist isoproterenol (25 nmol/liter). RESULTS: In the presence of 20 micrograms/ml of protamine, myocyte contractile function was unaffected in the control group but decreased by 40% from baseline values in the supraventricular tachycardia group. With 10 micrograms/ml of protamine, myocyte beta-adrenergic responsiveness was reduced by 25% in the supraventricular tachycardia group with no change in the control group. In the presence of 40 and 80 micrograms/ml of protamine, myocyte contractile function decreased in both groups. However, 40 micrograms/ml of protamine caused a more pronounced decline in myocyte function and beta-adrenergic responsiveness in the supraventricular tachycardia group. CONCLUSIONS: An increased sensitivity to the depressive effects of protamine on myocyte contractile function and beta-adrenergic responsiveness occurred in this model of chronic left ventricular dysfunction. These results suggest that patients with underlying cardiac disease may have an increased susceptibility to a sudden compromise of left ventricular contractile performance after protamine administration.

Animals↗

PubMed2006

Protamine enhances fibrinolysis by decreasing clot strength: role of tissue factor-initiated thrombin generation.

BACKGROUND: Excessive protamine administration to neutralize heparin after cardiopulmonary bypass has been implicated as a cause of postoperative hemorrhage. Protamine directly inhibits thrombin and tissue factor (TF)-mediated activation of factor VII. However, the half-life of protamine is only 4.5 minutes; thus the purpose of this study was to determine if protamine could enhance fibrinolysis, explaining the delayed, protamine-associated hemorrhage observed in the postoperative period. METHODS: Human plasma containing 0, 6.25, 12.5, or 25 microg/mL of protamine (n = 6 per condition) was exposed to 0.01% tissue factor and tissue-type plasminogen activator (tPA, 100 U/mL) for 30 minutes, with clot growth and disintegration measured by Thromboelastograph (Haemoscope Corp, Skokie, IL). The TF was increased to 0.1% in additional experiments with plasma containing protamine (25 microg/mL) and tPA. RESULTS: Protamine significantly (p < 0.05) delayed the time to clot initiation, decreased the speed of clot propagation, and diminished clot strength in a concentration-dependent fashion. The onset of fibrinolysis was significantly (p < 0.05) increased only in samples with 25 microg/mL of protamine, and the rate of clot lysis was not different among the conditions. The clot duration time (from initiation to disintegration) was significantly (p < 0.05) decreased in a concentration-dependent manner by protamine. Increased TF concentration (0.1%) significantly improved clot growth kinetics and prolonged clot duration in samples with 25 microg/mL of protamine compared with samples activated with 0.01% TF. CONCLUSIONS: Protamine enhanced fibrinolysis by decreasing clot strength by diminishing TF-initiated thrombin generation. Additional, clinical investigation is warranted to mechanistically implicate protamine-mediated enhancement of fibrinolysis to delayed bleeding after cardiopulmonary bypass.

Blood Coagulation↗

PubMed1996

Effects of differing rates of protamine reversal of heparin anticoagulation.

BACKGROUND: Protamine sulfate reversal of heparin anticoagulation may be associated with adverse cardiovascular side effects. The purpose of this study was to determine whether diminished systemic oxygen consumption and hemodynamic changes were more likely to accompany rapid versus slow protamine administration. METHODS: Fifteen patients undergoing abdominal aortic aneurysm resection in a prospective randomized double-blinded study received intravenous protamine (1.5 mg/kg) rapidly during a 3-minute period (group I, n = 7) or slowly during a 15-minute period (group II, n = 8). Systemic oxygen consumption (VO2) and hemodynamic parameters were assessed for up to 20 minutes after protamine administration began. RESULTS: Blood pressure declines (millimeters of mercury) were greatest in group I with rapid protamine administration (-19 systolic and -9 diastolic) compared with group II with slow protamine administration (-12 systolic and -1 diastolic). Heart rate fell markedly in both groups I and II. Cardiac output (CO) declined in group I at virtually all time periods. Similar CO declines in group II occurred 10 minutes after protamine infusion had begun and persisted for 3 minutes after protamine administration was complete. Maximum VO2 decreases were -16% (60 seconds into protamine infusion) and -13% (1.5 minutes after protamine infusion) in groups I and II, respectively, with statistically significant declines (p < 0.05) occurring only in group I compared with baseline values. Statistically significant differences (p < 0.01), however, were found when mean declines during and after protamine infusion were compared with controls for both CO and VO2 in both groups. CONCLUSIONS: Significant declines in systemic VO2 and hemodynamic perturbations accompany protamine reversal of heparin anticoagulation during aortic surgery. Rapid protamine administration increases the magnitude of these adverse responses.

Aged↗

PubMed1990

Protamine antibody production in diabetic subjects treated with NPH insulin.

Treatment with neutral protamine Hagedorn (NPH) insulin predisposes individuals with diabetes to anaphylactoid reactions when given bolus protamine for heparin reversal during cardiovascular procedures. To prospectively examine production of protamine antibodies, 30 patients with non-insulin dependent diabetes were followed for 12 months from initiation of therapy with porcine NPH or Lente insulin. Twenty-one subjects were randomly assigned to NPH (protamine containing) and nine controls to Lente (protamine free) insulin. Protamine specific IgG antibody was produced by 6/21 (29%) of NPH-treated subjects and 0/9 controls. Among NPH treated subjects, there was no difference between protamine antibody producers and non-producers with regard to age, race, weight, or pre-treatment glycosylated hemoglobin. Both producer and non-producer groups received similar amounts of insulin and protamine and achieved similar glycemic control. Insulin antibodies were made by 4/6 (67%) of protamine antibody producers and by 6/15 (40%) of non-producers (NS). The authors conclude that one of three new diabetics who are treated with porcine NPH insulin will make IgG protamine antibodies. These antibodies do not affect insulin requirements, glycemic control, or insulin antibody production. Because of the frequency of protamine antibody production and the risk of anaphylaxis to bolus protamine administration in NPH treated diabetics, the authors suggest that NPH insulin-treated individuals should avoid heparin reversal by protamine.

Diabetes Mellitus, Type 2↗

PubMed2002

The pharmacokinetics and cardiovascular effects of a single intravenous dose of protamine in normal volunteers.

UNLABELLED: Despite its long use in clinical medicine, protamine concentrations and pharmacokinetics in humans have not been reported. The occasional reoccurrence of anticoagulation after protamine reversal of heparin led us to hypothesize that protamine plasma concentrations decrease rapidly. We developed a method for the measurement of protamine in plasma. Eighteen fit volunteers gave their consent to receive 0.5 mg/kg protamine sulfate administered IV by an infusion pump over 10 min. Heart rate, mean arterial blood pressure, and cardiac output, all measured noninvasively, were recorded and blood samples obtained during and after protamine infusion. Blood plasma was subjected to solid-phase extraction and high-performance liquid chromatography. The administration of protamine was associated with no significant changes in heart rate, mean arterial blood pressure, or cardiac output. Plasma protamine concentrations decreased rapidly, becoming nondetectable within approximately 20 min. Protamine elimination differed significantly between men and women: men had significantly larger areas under the concentration versus time curve. Model-independent pharmacokinetic analysis revealed median (range) values as follows: volume of distribution at steady state, 12.3 (6.9--63.1) L; clearance, 2.2 (1.1--12.1) L/min; and t1/2, 7.4 (5.9--9.3) min. Concentration versus time plots revealed an atypical pattern inconsistent with usual exponential models. The Schwartz-Bayesian criterion identified a one-compartment Michaelis-Menten model and a two-compartment exponential model with irreversible binding as performing better than conventional one- or two-compartmental exponential models; however, performance errors were large with both Michaelis-Menten and exponential models. All models described rapid decreases in protamine blood concentrations. IMPLICATIONS: We developed a method for measurement of protamine in human blood. In volunteers, protamine concentrations decreased rapidly after administration. The rapid disappearance of protamine from the circulation, as defined by a median half-life of 7.4 min, could contribute to cases of "heparin rebound" after initial adequate reversal of heparin.

Adult↗

PubMed1991

Effects of protamine on vascular smooth muscle of rabbit mesenteric artery.

Systemic hypotension is commonly observed in association with protamine administration after cardiopulmonary bypass. However, little information is available concerning the action of protamine on vascular smooth muscle. Thus, we investigated the action of protamine on vascular tissues using tension recording and microelectrode methods. Protamine (5-500 micrograms/ml) inhibited contractions induced by norepinephrine (NE)- or elevated K+ in a concentration-dependent manner in both endothelium-intact and -denuded strips. Protamine inhibition of NE contractions was less profound after endothelial denudation, whereas protamine inhibition of K(+)-induced contractions was less affected by prior denudation. In endothelium-intact strips, the protamine-induced inhibition was significantly reduced by inhibitors of the endothelium-derived relaxing factor pathway, including oxyhemoglobin, methylene blue, or NG-nitro-L-arginine, whereas the contractile inhibition was enhanced by superoxide dismutase. In endothelium-denuded strips, protamine inhibited Ca(2+)-induced contraction evoked in Ca(2+)-free solution containing 100 mM K+ and inhibited the NE-induced contraction under the following conditions: 1) in Ca(2+)-free solution; 2) after nifedipine treatment; and 3) after depletion of stored Ca2+ by A23187 or ryanodine. In membrane-permeabilized strips, protamine did not modify Ca(2+)-induced contraction. Protamine (50-500 micrograms/ml) did not modify the membrane potential of either endothelium-intact or -denuded strips. Furthermore, protamine irreversibly impaired acetylcholine-induced endothelium-dependent relaxant response, implying a toxic effect of protamine on the endothelium. We conclude that protamine exerts its inhibition on vascular smooth muscles in both an endothelium-dependent and -independent manner; i.e., the endothelium-dependent component is mediated probably by endothelium-derived relaxing factor, and direct smooth muscle effects are due to the inhibition of both Ca(2+)-influx and the NE-induced Ca2+ release from intracellular stores.

Animals↗

PubMed2001

Role of heparin and nitric oxide in the cardiac and regional hemodynamic properties of protamine in conscious chronically instrumented dogs.

BACKGROUND: Because protamine is administered to reverse heparin, a drug that might itself affect the pharmacologic properties of protamine, this study was designed to assess the properties of protamine alone and in the presence of heparin in conscious dogs. METHODS: Twelve dogs were instrumented to continuously record cardiac and regional hemodynamics. On separate occasions, a dose of protamine (0.5, 1, 3, 5, and 8 mg/kg) was randomly administered either alone or in the presence of heparin (ratio 100 IU/mg). Heparin (300 IU/kg) and protamine (3 mg/kg) were administered in the presence of N-methyl-L-arginine, a specific nitric oxide synthase inhibitor. Identical experiments were performed with protamine (8 mg/kg) in the absence of heparin on a separate occasion. RESULTS: Protamine alone produced limited cardiac and regional changes. In the presence of heparin, protamine produced hypotension at 3, 5, and 8 mg/kg, vasodilatation at 3 and 5 mg/kg, and a more pronounced dose-dependent increase in pulmonary pressure at 3, 5, and 8 mg/kg. Simultaneously, transient carotid vasodilatation at 3 and 5 mg/kg, coronary and hepatic vasodilatation at 3, 5, and 8 mg/kg, as well as a decrease in vertebral vascular resistance were recorded at 1, 3, and 8 mg/kg. Protamine produced an immediate increase followed by a secondary decrease in renal vascular resistance. Protamine-induced secondary pulmonary pressor effects were attenuated. In the presence of heparin, nitric oxide synthase blockade selectively attenuated protamine-induced immediate hypotension, systemic vasodilatation, and coronary, mesenteric, and hepatic vasodilations as well as the decrease in portal blood flow and accentuated the renal vasoconstriction. CONCLUSIONS: The presence of heparin accentuated the decrease in cardiac function induced by protamine as well as its effects on regional circulation. The data provide evidence that the nitric oxide pathway is involved in the systemic and selective regional heparin-protamine-mediated vasodilatation in conscious dogs.

Animals↗

PubMed1990

PAF potentiates protamine-induced lung edema: role of pulmonary venoconstriction.

We studied the synergistic interaction between platelet-activating factor (PAF) and protamine sulfate, a cationic protein that causes pulmonary endothelial injury, in isolated rat lungs perfused with a physiological salt solution. A low dose of protamine (50 micrograms/ml) increased pulmonary artery perfusion pressure (Ppa) but did not increase wet lung-to-body weight ratio after 20 min. Pretreatment of the lungs with a noninjurious dose of PAF (1.6 nM) 10 min before protamine markedly potentiated protamine-induced pulmonary vasoconstriction and resulted in severe lung edema and increased lung tissue content of 6-keto-prostaglandin F1 alpha, thromboxane B2, and leukotriene C4. Pulmonary microvascular pressure (Pmv), measured by double occlusion, was markedly increased in lungs given PAF and protamine. These potentiating effects of PAF were blocked by WEB 2086 (10(-5) M), a specific PAF receptor antagonist. Pretreatment of the lungs with a high dose of histamine (10(-4) M) failed to enhance the effect of protamine on Ppa, Pmv, or wet lung-to-body weight ratio. Furthermore, PAF pretreatment enhanced elastase-, but not H2O2-, induced lung edema. To assess the role of hydrostatic pressure in edema formation, we compared lung permeability-surface area products (PS) in papaverine-treated lungs given either protamine alone or PAF + protamine and tested the effect of mechanical elevation of Pmv on protamine-induced lung edema. In the absence of vasoconstriction, PAF did not potentiate protamine-induced increase in lung PS. On the other hand, mechanically raising Pmv in protamine-treated lungs to a level similar to that measured in lungs given PAF + protamine did not result in a comparable degree of lung edema. We conclude that PAF potentiates protamine-induced lung edema predominantly by enhanced pulmonary venoconstriction. However, a pressure-independent effect of PAF on lung vasculature cannot be entirely excluded.

Animals↗

PubMed1990

Pulmonary hypertension after heparin-protamine: roles of left-sided infusion, histamine, and platelet-activating factor.

Severe pulmonary hypertension after protamine neutralization of heparin is an infrequent but life-threatening event following cardiopulmonary bypass. The effect of left ventricular infusion of protamine on pulmonary hypertension as well as a possible role of platelet-activating factor (PAF) or histamine in the heparin-protamine reaction was investigated in 30 pigs in four different groups during general anesthesia. Group 1 animals received 250 IU/kg heparin, followed by 100 mg protamine intravenously after 15 min. In group 2 protamine was infused into the left ventricle. Group 3 animals received the histamine H1- and H2-antagonists clemastine and ranitidine 5 min before protamine infusion. In group 4 the PAF receptor blocker WEB 2086 was given 5 min before protamine. Platelet-activating factor was measured by a bioassay in serum samples of group 1 and group 4 animals. In all four groups protamine caused severe pulmonary hypertension, thromboxane A2 release, and a transient decrease in leukocyte counts. No PAF release was detected after protamine infusion. Neither left ventricular infusion of protamine nor histamine or PAF antagonists prevented or attenuated the reactions after protamine infusion. The authors conclude that left ventricular infusion of protamine provides no protection from pulmonary hypertension, and that histamine and PAF are not involved in the acute pulmonary vasoconstriction after protamine neutralization of heparin.

Animals↗

PubMed1999

Aspects of mammalian spermatogenesis: electrophoretical analysis of protamines in mammalian species.

Protamines are small, highly basic proteins that replace histones and testicular basic proteins during the development of mature spermatozoa, spermatogenesis. In mammals, extensive disulfide crosslinking of protamines result in the formation of a compact chromatin structure devoid of transcriptional activity. As determined by isolation and electrophoresis of protamines, only one protamine has been detected in the mature spermatozoa of most mammalian species. However, in the spermatozoa of the mouse and human, two different protamines called P1 and P2, have been found. In this report we demonstrated by electrophoretic analysis that these two protamines are also present in the spermatozoa of Microtus arvalis, Microtus agretis, Apodemus flavicollis, Apodemus sylvaticus, Clethrionomys glareolus, the Chinese and the golden hamster. However, only one protamine is found in the spermatozoa of the guinea pig, dog, bull, black monkey, and the rhesus monkey. The mammalian protamines are highly conserved during mammalian evolution. In general, the homologies on the amino acid sequence of the various mammalian protamines range from 52% to 96%. Furthermore, in the case of mouse and human protamines, the genes of the protamines are closely linked and located on chromosome 7 and 16, respectively. Accordingly, it can be assumed that both types of protamine genes have arisen by gene duplication during mammalian evolution. According to the results of an electrophoretical analysis of the mammalian protamines, the predicted point of gene duplication during evolution is deduced carefully.

Amino Acid Sequence↗

PubMed2000

Requirement of protamine for maintaining nuclear condensation of medaka (Oryzias latipes) spermatozoa shed into water but not for promoting nuclear condensation during spermatogenesis.

Protamine is an arginine-rich basic protein found in the sperm nuclei of many vertebrates, but its actual roles in spermatozoa remain to be elucidated. In this study, we investigated the physiological roles of protamine by examining protamine-less spermatozoa produced in vitro in the presence of the transcriptional inhibitor actinomycin D. Even under inhibited transcription, medaka spermatocytes underwent meiosis and differentiated into spermatozoa with a condensed nucleus and an elongated flagellum. Using a newly produced anti-medaka protamine antibody, we confirmed the absence of protamine protein in the spermatozoa differentiated in the presence of actinomycin D. These findings clearly indicate that sperm nuclear condensation in medaka is independent of protamine. Since medaka spermatozoa are shed into water upon natural fertilization, we also investigated the roles of protamine by comparing the differences between the nuclear morphology of protamine-equipped and protamine-less spermatozoa immersed in water. The nuclei without protamine more rapidly swelled than did those with protamine and completely broke down within 10 min, whereas more than 80% of the sperm nuclei with protamine resisted the disruption under similar conditions. These findings strongly suggest that a physiological role of protamine in medaka spermatozoa is to protect the ejaculated spermatozoa against the disruption by low osmotic pressure until arrival at the eggs for successful fertilization.

Animals↗