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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. A Valsalva-like manoeuvre was used to elicit graded rises in total peripheral resistance (TPR) in conscious rabbits. The rises were reflex and mediated through sympathetic constrictors. Propranolol infused at different rates reaching plasma concentrations up to 240 (SEM 33) ng/ml had no effect on this reflex but reduced mean arterial pressure. However, the response was attenuated by clonidine in a dose-dependent manner. 2. Valsalva manoeuvres were used to elicit graded sympathetically mediated rises in TPR index in twenty-nine subjects with mean arterial pressure ranging from 75 to 165 mmHg. Absolute sensitivity of the constrictor response increased with rising resting TPR index, resulting in some enhancement of constrictor responses in the hypertensive subjects. It seems likely that non-autonomic factors (e.g. vessel structure) rather than hyperactive neural constrictor effects are involved in the enhanced constrictor responses in essential hypertension.
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PMID:Valsalva vasoconstrictor reflex in human hypertension in after beta-adrenoreceptor blockade in conscious rabbits. 1 55

A cell line from the intima of the rabbit aorta has been established. This cell line exhibits strict contact inhibition, and morphologically resembles intimal endothelial cells. B-type blood group antigens and the presence of fibrinolytic activity also distinguish these cells from smooth muscle cells and from fibroblasts of the aortic wall. Endothelial cells were assayed for changes in levels of adenosine 3':5'-cyclic monophosphate (cAMP) and guanosine 3':5'-cyclic monophosphate (cGMP) in response to a series of vasoactive drugs. Control levels for cAMP and cGMP are 7.01 +/- 0.82 and 1.50 +/- 0.06, respectively (mean +/- SEM). Norepinephrine, acetylcholine, 5-hydroxytryptamine, and phenylephrine increased the levels of both nucleotides significantly. Propranolol (10-5 M) and phentolamine (10-5M) inhibited, respectively, the cAMP and cGMP response to norepinephrine. Angiotensin II and histamine significantly increased cGMP levels but not cAMP levels of the endothelial cells. The cGMP increases with acetylcholine were inhibited by atropine. These results indicate that the established cell line is endothelial in nature and contains cellular receptors to a variety of vasoactive agents.
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PMID:Hormone and neurotransmitter receptors in an established vascular endothelial cell line. 17 91

The aim of this study was to compare the metabolic and hormonal effects of somatostatin to those of propranolol, a beta-adrenergic blocking agent known to reduce basal insulin secretion. For this purpose, 6 normal subjects received somatostatin (4 microgram/min) per 60 min and 6 subjects were infused with propranolol (0.08 mg/min). Somatostatin resulted in a significant decrease of basal insulin (p less than 0.05) and glucagon (p less than 0.01) and raised plasma FFA levels from a mean basal value of 417 +/- 24 muEq/1 (x +/- SEM) to 600 +/- 46 muEq/1 at 60 min (p less than 0.01). Propranolol significantly decreased basal insulin (p less than 0.05) and glucagon (p less than 0.05); FFA levels rose slightly at the end of propranolol administration (p less than 0.05). The levels of FFA which were significantly higher (p less than 0.025) during somatostatin as compared to those observed during propranolol, seem to suggest a role for this tetradecapeptide in lipid metabolism independent of its inhibiting action on islet hormone release.
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PMID:A comparative study of metabolic and hormonal responses to somatostatin and propranolol in man. 45 22

Chronic, low-grade, unexplained increases of total serum bilirubin concentration were observed in 16 of 132 (12%) chronic dialysis patients. Cessation of antihypertensive medication in four patients resulted in disappearance of hyperbilirubinemia. Propranolol was the only antihypertensive drug common to all 16 patients. Daily dosage varied among the patients, but the mean dose was 308 mg (+/- 51 SEM). Serial determinations of sera from individual patients given different doses and from the group as a whole demonstrated a linear relationship between propranolol dose and apparent total serum bilirubin concentration with continuous-flow analysis. When serum specimens from uremic patients receiving propranolol were treated with diazotized fulfanilic acid and examined spectrophotometrically, an absorbance peak distinct from but overlapping that of bilirubin was consistently demonstrated. The material producing the peak disappeared when the drug was stopped, did not dialyze, and was not reproduced by the in vitro addition of propranolol to uremic serum. We postulate that a metabolite(s) of propranolol is retained in uremic serum and interferes with the bilirubin determination.
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PMID:Spurious hyperbilirubinemia in uremic patients on propranolol therapy. 47 26

Propranolol alone was used to prepare 20 thyrotoxic patients, 19 women and 1 man, for subtotal thyroidectomy. Serum thyroxine (T4) and triiodothyronine (T3) concentrations were measured immediately before, at several stages during and after the surgical procedure. As judged primarily by the cardiovascular response, an average of 80 mg (range 40 to 120 mg) of propranolol qid for 8 days (range 3 to 18 days) was required to prepare the patients. During the various stages of surgical removal there was no change from the initial mean (+/- SEM) T4 concentration of 25.0 +/- 2.5 microgram/dl (321.8 +/- 32.2 nmol/l) or T3 concentration of 4.2 +/- 0.6 microgram/l (6.45 +/- 0.92 nmol/l) (P greater than 0.2). At discharge on the fifth postoperative day values were significantly lower, 12.9 +/- 1.5 microgram/dl (166.0 +/- 19.3 nmol/l) and 1.9 +/- 0.2 microgram/l (2.9 +/- 0.31 nmol/l), respectively (P less than 0.001). There were no operative complications but four patients had transient hypoparathyroidism. After 1 year 2 of 18 patients had permanent hypoparathyroidism and 4 of the 18 followed up for 1 year had permanent hypothyroidism requiring thyroid hormone replacement. There was no instance of recurrent thyrotoxicosis. The authors conclude that during surgical manipulation of the gland no release of thyroid hormones into the circulation was detected and that, using propranolol as the sole agent, thyrotoxic patients can be rapidly and safely prepared for subtotal thyroidectomy.
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PMID:Propranolol in thyrotoxicosis: II. Serum thyroid hormone concentrations during subtotal thyroidectomy. 58 22

A study, using non-invasive techniques, was carried out in ten patients with essential hypertension to examine the mechanism of the hypotensive effect of propranolol when used in combination with a potent vasodilator antihypertensive - minoxidil. The hypotensive effect of minoxidil, a mean (+/- SEM) decrease of 42.4 +/- 4.3 mm Hg, was accompanied by a marked increase in heart rate, cardiac index and plasma renin activity and a significant decrease in total peripheral resistance, limb vascular resistance and pre-ejection period. Addition of propranolol further reduced mean arterial pressure by an average of 12.9 +/- 2.0 mm Hg. Propranolol returned cardiac index to control values and total peripheral resistance index rose but not to control levels. Plasma renin activity was significantly reduced by propranolol. By multiple regression analysis no correlation was found between propranolol-induced decrease in mean arterial pressure and changes in cardiac index, total peripheral resistance index or plasma renin activity. Quantitatively, the reduction in cardiac index observed probably accounted for the hypotensive effect of propranolol. The role of plasma renin activity reduction in the hypotensive effect of propranolol in this situation remains to be clarified. The findings in the present study were consonant with the known actions of vasodilator antihypertensive agents and propranolol and indicate the applicability of non-invasive methodology to the investigation of cardiovascular drugs in man.
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PMID:Mechanism of the interaction of propranolol and a potent vasodilator antihypertensive agent - minoxidil. 97

A study was made of the possible mechanism(s) underlying minoxidil-induced increase in plasma renin activity (PRA). 10 patients with essential hypertension were treated with minoxidil and subsequently with a combination of minoxidil plus propranolol. Minoxidil lowered mean arterial pressure 31.6 plus or minus 3.3 mm Hg, mean plus or minus SEM. There was an associated increase in both PRA, 6.26 plus or minus 2.43 NG/ML/H, and heart rate, 21.4 plus or minus 2.7 beats/min. The changes in PRA and heart rate were positively correlated, r, 0.79. Addition of propranolol reduced mean arterial pressure by a further 10.1 plus or minus 1.5 mm Hg and returned heart rate to control levels. Propranolol reduced PRA significantly but not to control levels. Control PRA positively correlated with PRA on minoxidil, r, 0.97, and with PRA on minoxidil plus propranolol, r, 0.98. We conclude that control PRA is a major determinant of change in PRA with minoxidil. Minoxidil increased PRA by at least two mechanisms: (a) an adrenergic mechanism closely related to change in heart rate and blocked by propranolol, and (b) a mechanism(s) not sensitive to propranolol and possibly related to decrease in renal perfusion pressure.
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PMID:Control plasma renin activity and changes in sympathetic tone as determinants of minoxidil-induced increase in plasma renin activity. 112 99

The relationship between heart rate and left atrial end-diastolic diameter (LAEDD) and left atrial systolic shortening (LASS) was investigated in 12 conscious dogs. Atrial pacing, vagal blockade, isoproterenol, and beta-adrenergic blockade were used to change heart rate and the inotropic state of the atrium. LAEDD decreased linearly as heart rate increased. LAEDD averaged 33.0 mm (+/- 0.6 mm SEM) and decreased by 3.2 mm (+/- 0.4 mm SEM) with a change in heart rate of 50 beats/min. The ratio of LASS/LAEDD decreased as LAEDD decreased with increasing heart rate, but there was less of a reduction in the ratio at the extreme levels of LAEDD change with isoproterenol and vagal blockade. Propranolol reduced LASS at any LAEDD. At lower heart rates the reduction of LASS with pacing could be corrected by returning LAEDD to near control levels with a rapid infusion of fluid. It is concluded that LASS is primarily dependent on LAEDD and the inotropic state of the atrium. At higher heart rates, though, some effect of frequency can be observed. Isoproterenol and vagal blockade (increased contractile state) reduced the dependence of LASS on LAEDD.
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PMID:Effect of heart rate on left atrial systolic shortening in the dog. 114 Nov 26

Repeated acquisition behavioral performances of normotensive and renovascular hypertensive baboons were tested before, during, and following chronic oral dosing with the beta-adrenergic antagonists atenolol HCl (2.6 mg/kg/day PO), and d,l propranolol HCl (6.8 mg/kg twice daily PO) in separate studies. Each study administered active drug for 21 consecutive days preceded and followed by 14-day baseline and recovery periods, respectively. Animals pressed five keys in sequence for food reinforcement during daily experimental sessions which consisted of alternating acquisition (new sequence learning) and performance (previously learned) task components. Atenolol increased response latencies during acquisition in comparison to performance components, and during early portions of sessions. Propranolol also increased response latencies during acquisition components in early periods of sessions, but fewer dependent measures were affected, and the magnitude of increases in response latencies was smaller (12% +/- 5 SEM) as compared with atenolol (47% +/- 13). Test doses of phencyclidine HCl (PCP) increased latencies to the same degree as atenolol. PCP markedly reduced accuracy, while atenolol or propranolol did not. Blood pressures remained stable under atenolol, and decreased by approximately 10-15 mmHg under propranolol. No differences between renovascular hypertensive and normotensive baboons were found as a function of drug conditions. Drug effects were not dependent on plasma propranolol concentration.
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PMID:Performance of baboons under a repeated acquisition procedure during chronic oral exposure to atenolol and propranolol. 136 67

Binding studies with (-)-[125I]cyanopindolol (ICYP) were conducted to characterize beta-adrenoceptors in plantaris and soleus muscles of rats (male, 250-300 g). The distribution of beta 1- and beta 2-adrenoceptors in different muscle fiber types, identified in serial sections by succinic dehydrogenase (SDH) staining, was studied by autoradiography. The densities of binding sites (Bmax, fmol/mg protein) were 5.4 +/- 0.9 (mean +/- SEM) in plantaris and 11.5 +/- 2.0 in soleus muscle. In plantaris muscle, monophasic competition curves were observed when binding experiments were performed using CGP20712A (50 pM to 0.5 mM), a beta 1-adrenoceptor selective antagonist, or ICI 118,551 (50 pM to 20 microM), a beta 2-adrenoceptor selective antagonist, to compete for ICYP binding. Analysis with LIGAND revealed a single binding site with a KD value of 2.41 +/- 0.56 nM (mean +/- SEM) for ICI 118,551 and 8.93 +/- 3.00 microM for CGP 20712A, indicating the presence of a homogeneous population of beta 2-adrenoceptors. In soleus muscle, competition curves were biphasic with 16-21% beta 1-adrenoceptors. Autoradiographic studies supported the findings from binding studies with membrane homogenates. The ICYP binding pattern was associated closely with the muscle fiber types identified by SDH staining. Propranolol-resistant binding sites were observed, and these sites were associated with muscle fibers positive to SDH staining.
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PMID:Characterization of beta 1- and beta 2-adrenoceptors in rat skeletal muscles. 168 10


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