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Voltage jump analysis of procaine action at frog end-plate.

1. In the absence of procaine the end-plate conductance evoked by suberyldicholine increases exponentially to a new level following a step hyperpolarization. In the presence of procaine the suberyldicholine-evoked conductance first rapidly decreases and then slowly increases following a hyperpolarizing step. The fast relaxation has a time constant of approximately 1 msec, and the slow relaxation a time constant of 10-150 msec.2. The existence and sign of these two relaxations is predicted by a sequential model in which procaine enters and blocks open but not closed end-plate channels. The concentration dependence of the fast and slow relaxation time constants agrees well with the predictions of this model, and allows the apparent dissociation constant for binding of procaine within the open channel to be estimated at about 20 muM at -80 mV membrane potential.3. This apparent binding constant is voltage sensitive. It decreases e-fold for 50 mV hyperpolarization, suggesting that the procaine binding site is electrically half way through the channel.4. Procaine concentrations comparable to the dissociation constant for binding to open channels strongly depress the equilibrium current evoked by low suberyldicholine concentrations. This finding is not in accord with the sequential model.5. A cyclic model in which procaine binds to both closed and open channels explains well the equilibrium observations. The affinity of procaine for closed channels is similar to its affinity for open channels, and is also increased by hyperpolarization. This model also fits well the kinetic observations, if it is assumed that blocked channels open and close much more slowly than unblocked channels.6. The concentration dependence of the relaxation amplitudes disagrees with the predictions of the sequential model, but agrees well with the predictions of the cyclic model.7. No other model appears to explain the various observations as economically as the cyclic channel blocking model. If the model is correct the ;gate' controlling the end-plate channel must be in the inner half of the membrane.

Animals↗

Factors confounding blockade of cardiac afferents by intrapericardial procaine in conscious rabbits.

Intrapericardial procaine has been used by several groups to block cardiac afferent nerves to study effects of cardiogenic reflexes. In eight conscious rabbits, procaine (17-113 mg ipc; median 32) blocked cardiac efferents. Procaine (17-113 mg ipc; median 39) abolished the reflex depressor effects of the cardiac C-fiber excitant 1-phenylbiguanide (PBG), and in four of eight rabbits prevented the hypotensive phase 2 of acute central hypovolemia, which has been attributed to a signal from the heart. However, in three of the rabbits respiratory incoordination and blood gas abnormalities developed. In another study of four rabbits, procaine (165-335 mg ipc; median 235) invariably caused phrenic nerve blockade and underventilation. In three rabbits, after intrapericardial (250 mg) or subcutaneous (50 mg) procaine, plasma procaine levels rose to 9.4 and 4.8 micrograms/ml, respectively. During intravenous infusion of procaine, the PBG chemoreflex was abolished at plasma levels > 3.1 micrograms/ml, and phase 2 of acute hypovolemia at levels > or = 4.3 micrograms/ml. There is a narrow margin between a dose of intrapericardial procaine that blocks cardiac nerves and one that can produce confounding effects from phrenic nerve blockade or absorption into the bloodstream.

Animals↗

Procaine hydrochloride fails to relieve pain in patients with acute pancreatitis.

BACKGROUND: Several analgesics are in use for pain control in patients with acute pancreatitis. Procaine hydrochloride (procaine) has a long tradition and is recommended by the German Society of Gastroenterology and Metabolic Diseases for pain treatment in patients with acute pancreatitis. There is no controlled trial showing that procaine could be effective for pain treatment. METHODS: In an open, randomized, controlled trial, 107 patients (76 male, 31 female; mean age 45 +/- 12 years) were included and randomized either to receive procaine (n = 55) or pentazocine (n = 52) for pain relief. Procaine 2 g/ 24 h was administered by continuous intravenous infusion, pentazocine 30 mg was administered every 6 h as a bolus intravenous injection. Pentazocine was additionally administered on demand whenever required in patients of both treatment groups and its total consumption was recorded. Pain scores were assessed twice daily on a visual analogue scale. RESULTS: Patients receiving procaine were significantly more likely to request additional analgesics compared to patients treated with pentazocine alone, 98 vs. 44%, respectively (p < 0.001). Procaine did not reduce the amount of pentazocine required for pain control. The amount of pentazocine given in both groups was not statistically significantly different. Recorded pain scores were significantly lower (p < 0.001) in patients in the pentazocine group during the first 3 days of analgesic treatment. From day 4 on there was no significant difference in pain scores among the two groups. CONCLUSION: Thus, intravenous procaine treatment is not effective for pain control in patients with acute pancreatitis.

Acute Disease↗

Effects of caffeine and procaine on the membrane and mechanical properties of the smooth muscle cells of the rabbit main pulmonary artery.

Effects of caffeine and procaine on the membrane and mechanical properties of the smooth muscles of the rabbit main pulmonary artery were investigated using microelectrode and voltage clamp methods. Caffeine (greater than 0.5 mM) depolarized the membrane and increased ionic conductance. On the other hand, procaine (greater than 2.5 mM) depolarized the membrane, generated spikes and reduced the ionic conductance of the membrane. When depolarization-contraction relations were observed, the threshold depolarization to evoke contraction and the amplitude of the contraction were not affected by 5 mM procaine. However, the mechanical threshold was raised and the mechanical response was suppressed by treatment with 5 and 10 mM caffeine or 10 mM procaine. Procaine and caffeine accelerated the depletion of Ca++ from the stored sites of Ca-free (EGTA) solution, and suppressed the mechanical responses induced by chemical stimulation. Caffeine and procaine suppressed the increase in ionic conductance and depolarization produced by noradrenaline or prostaglandin F2alpha. Caffeine also suppressed the mechanical response induced by the above agents. Procaine suppressed the noradrenaline induced contraction, but accelerated the prostaglandin F2alpha induced contraction. From the above results, it is concluded that caffeine and procaine act not only on Ca-stored sites in the cell but also on the surface membrane. The actions of these agents were not competitive with each other, thus suggesting that the properties of the internal membrane structures, which is assumed to be a main Ca-storage site, are not exactly the same as those in striated muscles.

Animals↗

Effect of procaine on the pH of buffered and unbuffered cardioplegic solutions.

Changes in pH values were studied in two types of cardioplegic admixtures containing procaine 0.95 meq/L: an institutional formulation based on Ringer's injection and buffered with tromethamine injection 3.6%, and Plegisol (Abbott Laboratories) buffered with sodium bicarbonate injection 8.4%. Initial pH was measured in the buffered and unbuffered solutions before the addition of procaine and after the addition of 13 mL of procaine hydrochloride injection 2% or 260 mg of procaine hydrochloride powder (reference standard). Buffered 1-L admixtures containing procaine hydrochloride injection were stored (the institutional formulations in glass and the Plegisol admixtures in flexible plastic bags) at 3-5 degrees C or 25 degrees C. Plegisol admixtures were prepared with 10 mL (10 meq or 840 mg) of buffer as directed by the manufacturer or with 3 mL (3 meq) of buffer. Admixture pH was tested after various time intervals. Of the unbuffered solutions containing procaine, pH values were lower in Plegisol than in the institutional formulation. Of the procaine-containing buffered Plegisol solutions, only the admixture containing 3.0 mL of buffer and procaine prepared from powder had an initial pH in the acceptable range of 7.30-7.60. In all the stored solutions, pH changed rapidly; solution pH changed less under refrigeration. In the stored institutional admixtures, pH was acceptable for 96 hours at 3-5 degrees C and 24 hours at 25 degrees C. In the stored Plegisol admixtures to which 10 mL of buffer was added, pH was greater than 7.6 initially and continued to increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Bicarbonates↗

The reinforcing properties of procaine and d-amphetamine compared in rhesus monkeys.

Twelve rhesus monkeys were studied under a fixed-ratio (FR) schedule of intravenous procaine or d-amphetamine injection from 8 A.M. to 4 P.M. daily. Under the FR schedule, every nth lever press produced an injection. The FR value (n) and the dose per injection of procaine and d-amphetamine were varied systematically. At a FR value of 10, responding was maintained by doses of procaine ranging from 0.125 to 12 mg/kg/injection and by doses of d-amphetamine ranging from 0.01 to 0.1 mg/kg/injection. At doses of 1 mg/kg/injection of procaine and 0.1 mg/kg/injection of d-amphetamine, responding was maintained at FR values up to 100 by procaine and d-amphetamine but not by saline. Responding and drug intake were relatively constant throughout each 8-hour session with procaine, but responding tended to decrease and was more variable over the session with d-amphetamine. No toxic effects were observed in doses up to 6 mg/kg/injection with procaine. At this dose, eating and drinking ceased during the period of access to the drug. One of the four monkeys died at 8 mg/kg/injection of procaine. At 12 mg/kg/injection all three monkeys tested showed signs of toxicity.

Animals↗

Sodium and chloride dependency of dibucaine- and procaine-induced choleresis in isolated perfused rat livers.

The effect of local anesthetics, dibucaine and procaine, on hepatic bile formation was studied in the isolated perfused rat liver. Perfusate Na+ and Cl- were replaced by other ions to define the possible mechanism of action. A single dose (50 mumol) of dibucaine produced an initial cholestasis followed by choleresis. Whereas dibucaine produced only choleresis at a lower dose (10 mumol), only the cholestatic effect was seen at a higher dose (100 mumol). Procaine, on the other hand, produced only choleresis at all doses (1, 10 and 100 mumol); this choleresis was associated with biliary secretion of procaine and its metabolites. Neither dibucaine nor procaine affected the low endogenous bile acid secretion in these studies. The diffusion permeability coefficient of [carboxy-14C]inulin was not altered significantly by dibucaine and procaine, suggesting no significant alteration of biliary permeability. Biliary secretion of Na+ or Cl- declined during cholestasis and increased during choleresis. The initial cholestatic effect of dibucaine was still present when perfusates Na+ and Cl- were replaced by permeable Li+ or NO3-, but declined when Cl- was replaced by relatively impermeable isethionate, suggesting a nonspecific effect. The choleretic effect of both dibucaine and procaine, however, declined significantly when Na+ or Cl- was replaced by Li+, NO3- or isethionate-. These ion-substitutions did not affect significantly the biliary secretion of procaine and its metabolites. The ability to induce biliary secretion of Na+ and Cl- also decreased when Cl- was replaced by NO3- or isethionate and when Na+ was replaced by Li+, respectively. These results suggest that a part of the choleretic effect of both dibucaine and procaine is specifically dependent on Na+ and Cl-. This fraction is thus unlikely to be due to the osmotic effect of the secreted drug. Further studies showed that dibucaine inhibited Na+-dependent hepatic uptake of taurocholate, suggesting possible interference with other Na+-dependent transport processes. It is proposed that although a part of the choleresis is due to the osmotic effect of the secreted drug, the specific dependency of a portion of the choleretic effect on Na+ and Cl- is due to inhibition of Na+-coupled Cl- reabsorption from the canaliculi.

Animals↗

Anterior paralimbic mediation of procaine-induced emotional and psychosensory experiences.

BACKGROUND: Procaine activates limbic structures in animals. In humans, acute intravenous administration of procaine yields emotional and psychosensory experiences and temporal lobe fast activity. We studied procaine's acute effects on cerebral blood flow (CBF) in relationship to clinical responses. METHODS: Cerebral blood flow was assessed by positron emission tomography with oxygen-15-labeled water in 32 healthy volunteers. Data were analyzed with statistical parametric mapping and magnetic resonance imaging-directed regions of interest. RESULTS: Procaine increased global CBF and, to a greater extent, anterior paralimbic CBF. Subjects with intense procaine-induced fear compared with those with euphoria had greater increases in left amygdalar CBF. Absolute and normalized left amygdalar CBF changes tended to correlate positively with fear and negatively with euphoria intensity. Procaine-induced visual hallucinations appeared associated with greater global and occipital CBF increases. Absolute occipital CBF increases appeared to correlate positively with visual hallucination intensity. CONCLUSIONS: Procaine increased anterior paralimbic CBF, and different clinical responses appeared to be associated with different patterns of CBF changes.

Adolescent↗

Procaine inhibits the erythroid differentiation of MEL cells by blocking commitment: possible involvement of calcium metabolism.

The action of procaine on the terminal erythroid differentiation of murine erythroleukemia (MEL) cells has been investigated at the level of individual cells. At concentrations (7 X 10-4 M) which had no inhibitory effect on cell growth, pretreatment of these cells with procaine for 12-24 hr caused a pronounced inhibition ( greater than 90%) of commitment of terminal erythroid differentiation of dimethyl sulfoxide (DMSO)-treated cells. Simultaneous treatment of MEL cells with DMSO and procaine, however, resulted to only slight inhibition (less than 20%) of commitment. Blockade of commitment by procaine pretreatment appears to be general since it was observed in cells treated with other inducers (6-thioguanine, dimethylformamide). Procaine pretreatment did not abolish the ability of MEL cells to complete the "latent period" and commit upon the removal of the block. Reversal of procaine inhibition of commitment was obtained by the addition of either CaCl2 (1.0 mM), calcium ionophore A23817 (1 microgram/ml), but not of MgCl2 (1.0 mM). From these data we conclude that procaine inhibits the terminal erythroid differentiation of MEL cells by blocking an event or process required for commitment which occurs prior to commitment itself. Our results suggest that this process involves calcium metabolism.

Animals↗

Effects of procaine on intracellular pH and its regulation: measurements with pH-selective micro-electrodes in Retzius neurones of the leech.

The experiments were performed with double-barelled micro-electrodes in Retzius neurones of the leech in order to see if the tertiary amine local anesthetic procaine affects intracellular pH (pHi) and its regulation. Lasting about 20 min, exposures to procaine (3 mM) saline caused an intracellular alkalosis of about 0.2 pH units which gradually degradated; its removal initiated a fast decrease of pHi resulting in an acidosis, fron which the cells recovered. Detailed studies, involving CO2 or NH4+ acid loaded cells as well as inhibition of the pHi regulating exchange mechanism by various drugs or exposures to Na-free salines suggest, that neither the Na+ -H+, nor a probably Na+ -dependent HCO3-(-)Cl- exchange are affected by procaine. We propose a model for procaine action on pHi assuming that neutral procaine passes the membrane easily through lipophilic pathways. The degradation of alkalinity during procaine exposure hints on an entry of loaded procaine, some possible transport paths of which are discussed.

Animals↗

Saxitoxin and procaine act independently on separate sites of the sodium channel.

1. Voltage clamp experiments were done on single myelinated nerve fibres of the frog, Rana esculenta. 2. The time course of procaine action (1.0 mM at pH 7.2) was obtained from changes in INa on changing solutions during repetitive (1 HZ) depolarizing pulses of constant amplitude following hyperpolarizing prepulses. The mean half times of onset and offset of procaine block were 3.7 and 28 s, respectively. In the presence of 1.4 nM saxitoxin (STX) the corresponding times were virtually the same, 3.1 and 27 s. 3. Similarly, the time course of partial relief from procaine block that is obtained by increasing the frequency of the prepulse-test pulse pairs from 1-10 HZ was unaffected in the presence of STX. 4. Comparison of the equilibrium effects of procaine concentrations ranging from 0.03-1.0 mM suggest a one-to-one drug-receptor reaction. The fraction of Na channels blocked at equilibrium with 1.0 mM procaine, 1.4 nM STX, and 1.0 mM procaine + 1.4 nM STX was 0.81, 0.49, and 0.90, respectively. This result and the kinetic behaviour fully agree with the idea of two separate and independent receptors for procaine and STX.

Animals↗

Procaine-induced increases in limbic rCBF correlate positively with increases in occipital and temporal EEG fast activity.

Previous independent EEG and PET studies suggest that administration of intravenous procaine hydrochloride selectively activates limbic brain structures. To further elucidate procaine's effects and explore the relationship between quantitative EEG (qEEG) and regional cerebral blood flow (rCBF), we simultaneously recorded qEEG and sampled rCBF using O-15 water PET in 20 healthy volunteers during single-blind injections of saline (baseline condition) followed by intravenous procaine (1.84 mg/kg). After thorough screening of EEG records, a subgroup of 7 subjects with EEG data relatively free of both muscle and movement artifacts was selected for analysis. Quantitative spectral EEG data from right occipital and temporal leads were then correlated with each subject's PET rCBF values on a pixel by pixel basis, both at baseline and after procaine. The most striking finding was that the increases in occipital and temporal omega activity from baseline to procaine positively correlated with rCBF increases in the amygdala and its efferents (p < .05), in a pattern very similar to the rCBF increases seen after procaine administration. This suggests that omega activity may reflect activation of deeper brain limbic structures. Also, the convergence of EEG and PET data further supports procaine's selective limbic activation.

Adult↗

Procaine has opposite effects on passive Na and K permeabilities in frog skin.

Procaine has opposite effects on the active transport of Na+ when applied on the mucosal side of the frog skin [where it produces a stimulation of the short-circuit current (Isc)] or when added on the serosal side (where it produces an inhibition of Isc). In an attempt to reveal and localize the primary effect of procaine on either the apical or latero-basal membranes of the epithelial cells, we have tried to "chemically dissect" both membrane functions with inhibitors and ionophores. When applied on the apical side of the latero-basally depolarized epithelium, 25 mmol/l procaine increases Isc and Voc (transepithelial open-circuit potential), while decreasing the transepithelial resistance. The E1-E2 linearity domain of the I-V curves is narrowed. On the serosal side of the depolarized epithelium, the same concentration of procaine does not affect Isc and Voc (which are already inhibited) but it produces an increase in the transepithelial resistance (Rt). Procaine influence on the passive K+ permeability was studied by using the ionophore nystatin, which is assumed to form channels permeable to K+, when applied on the amiloride blocked apical membrane. In nystatin-treated epithelia, 25 mmol/l procaine on the apical side decreased Isc, Voc and Rt. In parallel experiments during Cl- substitution by SO2-(4), the procaine effects on Isc and Voc are no longer maintained, but transient.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗

Influence of stearic acid monolayers upon the procaine adsorption from underlying alkaline aqueous solutions.

Adsorption of procaine at the air/water interface and its penetration into stearic acid monolayers from aqueous subphase of pH 8 are studied by measuring surface tension of aqueous procaine solutions and by recording surface pressure vs. mean molecular area curves for stearic acid monolayers spread onto procaine solutions of different concentrations. The amount of procaine in the interface is derived by means of Gibbs' equation. Results are compared to those obtained earlier at pH 2 and on unbuffered subphases. With increasing pH an increasing procaine adsorption and procaine penetration is observed. This phenomenon is interpreted in terms of protolytic equilibria in which participate both surfactants procaine and stearic acid.

Adsorption↗

Procaine actions on tetrodotoxin sensitive and insensitive leech neurons.

Procaine (0.1-10 mM) was applied to two kinds of identified neurons in segmental leech ganglia. Both Retzius (R) cells and nociceptive (N) cells responded by dose-dependent reduction of maximum rates of de- and repolarization during action potentials. However, the N cells, which are more sensitive to tetrodotoxin than R cells, were also 3 times more sensitive to procaine. The prolongation of action potentials produced by procaine in R cells was enhanced by low Ca but antagonized by high Ca. This implies that the drug interfered with repolarization by affecting a Ca-dependent mechanism. In alkaline solution (pH 8.5), sensitivity of the R cell to procaine approached that of the N cell at pH 7.4 suggesting that the drug acted at an intracellular site after passage through membrane lipids in its uncharged form. The combined effects of TTX and procaine, in concentrations which produced about 50% inhibition of dV/dTdep in N cells when given separately, were found to be intermediate between those predicted by two models which assume identical and independent sites of action, respectively. These data extend our earlier observations regarding the existence of two types of Na channels in mature leech neurons. They imply that the differential sensitivity to procaine among these cells may be a consequence of variable access to an otherwise identical 'receptor' and that TTX and procaine act on separate sites which may interact with each other.

Animals↗

Reinforcing properties of intravenous procaine in rhesus monkeys.

The lever pressing behavior of rhesus monkeys was maintained by a fixed ratio 10 schedule of intravenous cocaine (3 monkeys) or codeine (2 monkeys) injections during 2 hour sessions. Saline or various doses of procaine hydrochloride were substituted for the baseline reinforcer for 6 consecutive sessions. Each substitution was separated by 3 or more days of cocaine or codeine reinforced responding. At one or more doses, procaine substitution resulted in response rates higher than saline control in all 5 animals. High response rates (greater than 30 injections per session) were obtained in 4 of the 5 monkeys. In addition, procaine self-administration was studied in two naive monkeys given 23 hour per day access to procaine following an initial 10 days of saline contingent operant level responding. At a dose of 0.3 mg/kg/injection, both animals initiated responding for procaine reinforcement. Drug intake varied widely from day to day, however each animal took over 1200 injections per day (over 360 mg/kg) at least once during the 30 days of access. With the exception of decreased food intake, there was little evidence for behavioral toxicity from these doses. Following a second 10 days of saline self-administration, both animals were given access to 3.0 mg/kg/injection procaine. A substantially greater intake of procaine was observed which was associated with marked toxicity.

Animals↗

Locomotor activity in morphine-treated rats: effects of and comparisons between cocaine, procaine, and lidocaine.

The effects of cocaine, procaine, and lidocaine on open field and spontaneous (actophotometer) locomotor activities were assessed and compared in rats (1) treated acutely with morphine (single injection), (2) made dependent on morphine (SC pellets), (3) implanted with morphine and withdrawn at the time of peak dependence, and (4) implanted SC with lactose-containing pellets (sham). Cocaine-induced (10 or 30 mg/kg) open field and spontaneous locomotor activities were significantly greater in each of the four groups than those of the corresponding groups administered saline. Procaine (50 or 100 mg/kg) significantly reduced open field locomotor activity in all morphine-treated rats and spontaneous locomotor activity in acute rats. Lidocaine (30 mg/kg) significantly depressed spontaneous locomotor activity in acute rats. Upon comparison of the activities induced by the three local anesthetics, open field locomotor activity of sham-implanted rats was greater following cocaine (10 or 30 mg/kg) than following procaine (50 or 100 mg/kg). Only morphine withdrawn rats manifested greater activity following cocaine (10 mg/kg) than following either procaine (50 mg/kg) or lidocaine (10 mg/kg); activities were equivalent in dependent and acute rats. In contrast, cocaine-induced (30 mg/kg) open field locomotor activity of all morphine-treated rats was greater than either procaine- (100 mg/kg) or lidocaine- (30 mg/kg) induced activities. Spontaneous locomotor activity of all groups except acute morphine was greater following both doses of cocaine than following both doses of either procaine or lidocaine. In acute rats, only cocaine (10 mg/kg, induced greater activity than the other local anesthetics. Thus, stimulation of locomotor activity following cocaine treatment is a pharmacological property unique to cocaine and not shared by either procaine or lidocaine. Further, the data indicate that the methods selected for assessing locomotor activity may not give comparable results.

Animals↗

Electrochemistry and voltammetry of procaine using a carbon nanotube film coated electrode.

A new rapid, convenient and sensitive electrochemical method is described for the determination of procaine in pharmaceutical preparations, based on the unique properties of a multi-wall carbon nanotube (MWNT) thin film. The electrochemical behavior of procaine at the MWNT film-coated glassy carbon electrode (GCE) was investigated in detail, showing that the MWNT-coated GCE exhibits electrocatalytic activity to the oxidation of procaine because of the significant peak current enhancement and the lowering of oxidation overpotential. Furthermore, the mechanism for the oxidation of procaine at the MWNT-coated GCE was also studied. Finally, various experimental parameters such as solution pH value, the amount of MWNT, accumulation conditions and scan rate were optimized for the determination of procaine, and a new method with detection limit of 2 x 10(-7) mol/L was developed for procaine determination. This newly proposed method was successfully demonstrated with procaine hydrochloride injection.

Biosensing Techniques↗