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R S Danziger

Publications and source records attributed to R S Danziger.

At least 19 recordsLinked to original sources
PubMed2000

Evaluation of heterodimeric guanylyl cyclase genes as candidates for human hypertension.

OBJECTIVE: Both physiologic and pharmacological data have implicated the nitric oxide (NO) signaling cascade in the regulation of blood pressure in humans and its impairment in the pathogenesis of hypertension. In biological systems, the principal receptor for NO is NO-stimulated guanylyl cyclase. NO-stimulated guanylyl cyclases are obligate heterodimers (alpha/beta). The genes for guanylyl cyclase subunits alpha1, beta, and beta2 are likely candidates for causing hypertension in the Dahl rat as their expression is altered and their gene loci are closely linked to known quantitative trait loci for blood pressure in Dahl rat crosses. The objective of the current study was to test whether markers near guanylyl cyclase subunit genes were linked to hypertension in Caucasians. DESIGN: To test for linkage of genetic markers in or near the guanylyl cyclase genes to hypertension in Caucasians, a sample of 124 Utah hypertensive sib pairs was genotyped. RESULTS: Four highly polymorphic markers in or near the human guanylyl cyclase subunits homologous to the rat alpha1 (human chromosome 8), rat beta1 (human chromosome 4), and rat beta2 (human chromosome 13) genes showed no evidence of excess allele sharing in the set of hypertensive sibships. CONCLUSION: We conclude that the heterodimeric guanylyl cyclase subunit loci do not appear to be linked to hypertension in Caucasians.

Adult↗
PubMed1998

Resonance Raman characterization of soluble guanylate cyclase expressed from baculovirus.

Resonance Raman spectra of the alpha 1 beta 1 isoform of bovine lung soluble guanylate cyclase expressed from baculovirus have been measured. The spectra show that the ferric heme is five-coordinate high spin whereas the ferrous heme in the absence of added exogenous ligands is a mixture of six-coordinate low spin and five-coordinate high spin. In the Fe-CO-derivative, the correlation between the Fe-CO frequency (497 cm-1) and the C-O frequency (1959 cm-1) demonstrates that the proximal ligand in our preparation is histidine. The Fe-NO stretching frequency (found at 520 cm-1) and other spectral features of the ferrous Fe-NO-bound sGC are similar to those reported by Deinum et al. (1) and Yu et al. (2). These data indicate that although large preparation-dependent differences in the occupancy of the distal pocket exist, all the preparations have the same proximal histidine ligation and share the same mechanism of activation by NO.

Animals↗
PubMed1998

Genetic mapping of soluble guanylyl cyclase genes: implications for linkage to blood pressure in the Dahl rat.

The nitric oxide (NO) signaling system, consisting of NO synthases, soluble guanylyl cyclase, and cGMP, plays a prominent role in salt handling and regulation of blood pressure. Soluble guanylyl cyclases are heme-containing heterodimers (alpha/beta). The alpha1/beta1 isoform has greater NO sensitivity than the alpha1/beta2. It has recently been shown that expression of the beta subunits is altered in the kidney of the Dahl salt-sensitive rat, ie, the beta1 subunit is decreased and the beta2 subunit increased. However, whether soluble guanylyl cyclase is linked to salt sensitivity is not known. In the present study, we investigated linkage of guanylyl cyclase genes to blood pressure. Alpha1 and beta1 gene loci for soluble guanylyl cyclase were mapped to rat chromosome 2, and the beta2 gene locus was mapped to rat chromosome 5 using fluorescent in situ metaphase hybridization. By use of a rat radiation hybrid panel, the gene loci were then further mapped with respect to known quantitative trait locus markers of salt-sensitive hypertension in the Dahl rat on chromosomes 2 and 5. Genes for alpha1 and beta1 were closely linked by two-point analysis to Na+,K+-ATPase alpha1 isoform (LOD of 15.1 and 14.0, respectively) and calmodulin-dependent protein kinase II-delta loci (LOD of 14.3 and 12.9, respectively), which have been previously shown to flank a quantitative trait locus for blood pressure in the Dahl rat. The alpha1 and beta1 genes were closely linked (LOD of 11.3; theta, 0.4). The beta2 gene locus was closely linked to the endothelin-2 (ET-2) locus (LOD of 13.0), which has been shown to cosegregate with blood pressure. We conclude that soluble guanylyl cyclase subunit loci, ie, alpha1, beta1, and beta2, are good candidates for genes controlling salt-sensitive hypertension in the Dahl rat.

Animals↗
PubMed1997

The beta2 subunit inhibits stimulation of the alpha1/beta1 form of soluble guanylyl cyclase by nitric oxide. Potential relevance to regulation of blood pressure.

Cytosolic guanylyl cyclases (GTP pyrophosphate-lyase [cyclizing; EC 4.6.1.2]), primary receptors for nitric oxide (NO) generated by NO synthases, are obligate heterodimers consisting of an alpha and a beta subunit. The alpha1/beta1 form of guanylyl cyclase has the greatest activity and is considered the universal form. An isomer of the beta1 subunit, i.e., beta2, has been detected in the liver and kidney, however, its role is not known. In this study, we investigated the function of beta2. Immunoprecipitation experiments showed that the beta2 subunit forms a heterodimer with the alpha1 subunit. NO-stimulated cGMP formation in COS 7 cells cotransfected with the alpha1 and beta2 subunits was approximately 1/3 of that when alpha1 and beta1 subunits were cotransfected. The beta2 subunit inhibited NO-stimulated activity of the alpha1/beta1 form of guanylyl cyclase and NO-stimulated cGMP formation in cultured smooth muscle cells. Our results provide the first evidence that the beta2 subunit can regulate NO sensitivity of the alpha1/beta1 form of guanylyl cyclase. Northern analysis for guanylyl cyclase subunits was performed on RNA from kidneys of Dahl salt-sensitive rats, which have been shown to have decreased renal sensitivity to NO. Compared to the Dahl salt-resistant rat, message for beta2 was increased, beta1 was decreased, and alpha1 was unchanged. These results suggest a molecular basis for decreased renal guanylyl cyclase activity, i.e. , an increase in the alpha1/beta2 heterodimer, and decrease in the alpha1/beta1 heterodimer.

Animals↗
PubMed1997

Expression and purification of soluble, active heterodimeric guanylyl cyclase from baculovirus.

A method for expression and purification of active cytosolic heterodimeric histidine (His)-tagged guanylyl cyclase of the alpha 1/beta 1 isoform has been developed using recombinant baculovirus-transfected insect cells. Confirmation of expression of active cyclase was obtained by both Western analysis and enzymatic activity. A His tag on the COOH-terminus of the alpha 1 and beta 1 subunits allowed rapid purification of the heterodimeric form of guanylyl cyclase in a single affinity step using a nickel column. A second gel-filtration step was applied to reconstitute into the complex heme, a required cofactor. This was confirmed spectroscopically by absorbance in the Soret region. Like enzyme purified from tissue, the activity of recombinant guanylyl cyclase was increased by protoporphyrin IX and inhibited by both Zn- and Sn-protoporphyrin. The method described here should provide a general approach for the expression and purification of alternate forms of cytosolic guanylyl cyclase and facilitate mechanistic and structural studies of this important family of enzymes. Furthermore, the procedure demonstrates the utility of the His-tag system to purify multimeric proteins.

Animals↗
PubMed1997

Role of nitric oxide in the regulation of osteoblast metabolism.

Nitric oxide has recently been shown to inhibit the proliferation of several types of cells, including osteoclasts. Both osteoclasts and osteoblasts have inducible nitric oxide synthase and produce nitric oxide. Although the direct effect of nitric oxide on osteoblasts in general and osteoblast proliferation in particular has not been delineated, the authors performed studies to clarify the role of nitric oxide on osteoblast proliferation and metabolism. Cultures of human osteoblasts were exposed to 0.1, 1.0, and 10 microM of the nitric oxide releasing agent 3-morpholino sydnonimine (SIN-1) for 7 days. Cells were evaluated for proliferation and production of alkaline phosphatase and osteocalcin. Osteoblasts exhibited decreased proliferation relative to control cultures at 1.0 and 10 microM concentrations of SIN-1 (p < 0.05). Concentrations of 1.0 and 10 microM of SIN-1 effected a decreased production of osteocalcin and alkaline phosphatase (p < 0.05). The results of these studies indicate that nitric oxide may play a critical role by which osteoblasts exhibit self-regulation of mineral metabolism.

Alkaline Phosphatase↗
PubMed1996

Hemodynamic and renal excretory effects of human brain natriuretic peptide infusion in patients with congestive heart failure. A double-blind, placebo-controlled, randomized crossover trial.

BACKGROUND: The pharmacological effects of infusion of human brain natriuretic peptide (hBNP) in patients with severe congestive heart failure have not been characterized previously. METHODS AND RESULTS: Twenty patients with severe congestive heart failure were randomized in a double-blind, placebo-controlled, crossover trial to receive incremental 90-minute infusions of hBNP (0.003, 0.01, 0.03, and 0.1 microgram/kg per minute) or placebo on 2 consecutive days. At the highest completed dose of the hBNP, mean pulmonary artery pressure decreased from 38.3 +/- 1.6 to 25.9 +/- 1.7 mm Hg; mean pulmonary capillary wedge pressure decreased from 25.1 +/- 1.1 to 13.2 +/- 1.3 mm Hg; mean right atrial pressure decreased from 10.9 +/- 1 to 4.8 +/- 1.0 mm Hg; mean arterial pressure decreased from 85.2 +/- 2.0 to 74.9 +/- 1.7 mm Hg; and cardiac index increased from 2.0 +/- 0.1 to 2.5 +/- 0.1 L/min per square meter (all P < .01 versus placebo). Urine volume and urine sodium excretion increased significantly during hBNP infusion when compared with placebo infusion (90 +/- 38 versus 67 +/- 27 mL/h and 2.6 +/- 2.4 versus 1.4 +/- 1.2 mEq/h, respectively, both P < .05 versus placebo), whereas creatinine clearance and urinary potassium excretion did not change. CONCLUSIONS: Infusion of incremental doses of hBNP is associated with favorable hemodynamic and natriuretic effects in patients with severe congestive heart failure.

Blood Pressure↗
PubMed1993

Characterization of soluble guanylyl cyclase in transformed human non-pigmented epithelial cells.

Topical application of nitro vasodilators, such as sodium nitroprusside, reduces intraocular pressure. In brain and blood vessels, nitro vasodilators activate soluble guanylyl cyclases, producing cGMP. The location and molecular identity of ocular guanylyl cyclases are unknown. We studied transformed human non-pigmented ciliary epithelial cells, whose parental cells are responsible for the production of aqueous humor. Sodium nitroprusside increased cGMP 40 to 60 fold in a time and concentration dependent manner (EC50 40 to 100 microM). Methylene blue inhibited this effect (IC50 0.6 microM in the presence of 100 microM sodium nitroprusside). We also detected mRNA for the alpha 1 and beta 1, but not the beta 2, subunit isoforms of soluble guanylyl cyclase in these cells by Northern blotting. We conclude that transformed non-pigmented epithelial cells contain an active heterodimeric soluble guanylyl cyclase composed of at least alpha 1 and beta 1 subunits.

Blotting, Northern↗
PubMed1992

Contractile response of individual cardiac myocytes to norepinephrine declines with senescence.

The present study utilized individual isolated left ventricular cardiac myocytes from hearts of animals of a broad age range to evaluate the response to norepinephrine and to other stimuli that augment myocardial cell contractile performance. During electrical stimulation before drugs neither the amplitude nor the velocity of shortening normalized for resting cell length differed among cells isolated from 2-, 6- to 8-, or 24-mo-old animals. Norepinephrine augmented twitch amplitude and velocity about fourfold in cells from 2-mo-old hearts but only by 2.5-fold in cells from 24-mo-old hearts (age effect, P less than 0.001). In contrast, the contractile response to increases in bathing [Ca2+] or to the addition of the calcium channel agonist BAY K 8644 or of 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (CPT cAMP) did not vary with age. These results indicate that the age-associated contractile deficit during beta-adrenergic stimulation is specific to the beta-adrenergic pathway and an age-associated deficit in the net production of cAMP. This can be attributed to a diminished cardiac myocyte response to beta-adrenergic agonists, in contrast to modulation of the beta-adrenergic response by other receptor agonists, which are present in intact tissue but absent under the conditions of the present study.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

Ethanol acutely and reversibly suppresses excitation-contraction coupling in cardiac myocytes.

We used adult rat cardiac myocytes to examine the acute effects of 0.1-5.0% (vol/vol) ethanol (ETOH) on 1) the cytosolic [Ca2+] (Cai) transient measured as the change in indo 1 fluorescence at 410/490 nm and contraction elicited by electrical stimulation of single cells and 2) the sarcoplasmic reticulum (SR) Ca2+ content in cell suspensions. During stimulation at 1 Hz, clinically relevant ETOH correlations (0.1-0.15% [vol/vol]) caused a 10-15% decrease in the contraction amplitude, measured by myocyte edge tracking, without decreasing the Cai transient that initiates contraction. At higher ETOH concentrations (1-5% [vol/vol]), ETOH caused profound contractile depression and also reduced the magnitude of the Cai transient. These effects were reversed within minutes of ETOH washout. Addition of norepinephrine (10 microM) to the bathing solution or an increase in bathing [Ca2+] in the continued presence of ETOH could also reverse its effects. The relation of the amplitude of the Cai transient to the contraction amplitude measured across a range of bathing [Ca2+] was shifted by ETOH, such that for a given Cai transient a marked reduction in contraction amplitude occurred. In unstimulated myocyte suspensions, ETOH (1-5% [vol/vol]) caused a concentration-dependent depletion of SR Ca2+ content, manifested as a diminution in the Cai increase elicited by caffeine in the presence of extracellular EGTA and no added Ca2+. Thus, in rat cardiac myocytes a reduction in the myofilament Ca2+ response, possibly due to a decrease in myofilament Ca2+ sensitivity, is a mechanism for contractile depression due to clinically relevant ETOH concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Potentiation of cocaine-induced coronary vasoconstriction by beta-adrenergic blockade.

STUDY OBJECTIVE: To determine whether beta-adrenergic blockade augments cocaine-induced coronary artery vasoconstriction. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: A cardiac catheterization laboratory in an urban teaching hospital. PATIENTS: Thirty clinically stable patient volunteers referred for catheterization for evaluation of chest pain. INTERVENTIONS: Heart rate, arterial pressure, coronary sinus blood flow (by thermodilution), and epicardial left coronary arterial dimensions were measured before and 15 minutes after intranasal saline or cocaine administration (2 mg/kg body weight) and again after intracoronary propranolol administration (2 mg in 5 minutes). MEASUREMENTS AND MAIN RESULTS: No variables changed after saline administration. After cocaine administration, arterial pressure and rate-pressure product increased; coronary sinus blood flow fell (139 +/- 28 [mean +/- SE] to 120 +/- 20 mL/min); coronary vascular resistance (mean arterial pressure divided by coronary sinus blood flow) rose (0.87 +/- 0.10 to 1.05 +/- 0.10 mm Hg/mL.min); and coronary arterial diameters decreased by between 6% and 9% (P less than 0.05 for all variables). Subsequently, intracoronary propranolol administration caused no change in arterial pressure or rate-pressure product but further decreased coronary sinus blood flow (to 100 +/- 14 mL/min) and increased coronary vascular resistance (to 1.20 +/- 0.12 mm Hg/mL.min) (P less than 0.05 for both). CONCLUSIONS: Cocaine-induced coronary vasoconstriction is potentiated by beta-adrenergic blockade. Beta-adrenergic blocking agents probably should be avoided in patients with cocaine-associated myocardial ischemia or infarction.

Adrenergic beta-Antagonists↗
PubMed1990

Assessment of the sensitivity of hydrogen inhalation in the detection of left-to-right shunting.

For the detection of left-to-right intracardiac shunting, the oximetric and standard indocyanine green techniques are relatively insensitive, in that neither can reliably detect a shunt with a ratio of pulmonary to systemic flow (Qp/Qs) less than 1.3 (percentage shunt, 23%). Although the hydrogen inhalation method is said to be much more sensitive in this regard, no previous study has measured its sensitivity. Accordingly, in 15 patients (4 men, 11 women, aged 38 to 67 years) without intracardiac shunting, hydrogen inhalation was performed 1) without and 2) with an artificially created femoral arteriovenous shunt of known size, and cardiac output was measured by thermodilution. For the 15 subjects with cardiac outputs of 3.64 to 8.10 liters/min, shunts of 22 to 248 ml/min were created, so that the shunts ranged from 0.5% to 3.3%. Hydrogen inhalation detected all shunts greater than or equal to 1.3% (Qp/Qs greater than or equal to 1.01). Of the 10 shunts less than 1.3%, it detected 5, with the smallest being 0.7%. Thus, the hydrogen inhalation technique is extremely sensitive in identifying the presence of left-to-right shunting, far more sensitive than the oximetric and standard indocyanine green methods.

Adult↗