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

Beta 2 as well as beta 1 adrenoceptors have been recognized in the heart of vertebrates. They mediate a positive chronotropic action of catecholamines. We compared the effect of selective beta 1 and beta 2 adrenoceptor antagonists on the genesis of halothane-epinephrine arrhythmias in dogs. The arrhythmogenic dose (AD) of epinephrine was increased in the presence of l-metoprolol, a selective beta 1 antagonist (8.40 +/- 1.13 micrograms.kg-1 x min-1; mean +/- SEM), compared with control value (2.62 +/- 0.56) (P < 0.05). In contrast, ICI-118,551, a selective beta 2 antagonist, did not change the AD (2.36 +/- 0.43). Adding ICI-118,551 to l-metoprolol did not affect the AD of epinephrine in the presence of l-metoprolol alone (6.34 +/- 0.74 vs 8.40 +/- 1.13). These results suggest that selective beta 1 blockade is effective in preventing halothane-epinephrine arrhythmias, but selective beta 2 blockade is not.
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PMID:Selective beta 1 and beta 2 adrenoceptor blockade on epinephrine-induced arrhythmias in halothane anaesthetized dogs. 128 41

Nebivolol, a chemically novel beta 1-adrenoceptor antagonist, acutely lowers blood pressure in spontaneously hypertensive rats, anaesthetised normotensive dogs, and hypertensive patients. We have investigated the actions of dl-nebivolol in five conscious normotensive rabbits (sham, mean blood pressure (BP) of 82.2 +/- 4.1 mm Hg, mean +/- SEM) and four hypertensive rabbits (renal wrap hypertension) (wrap, mean BP of 117.6 +/- 1.5 mm Hg). Nebivolol (1 mg/kg i.v.) did not significantly lower the BP or heart rate in either group 30 min after injection. In the same rabbits, on another day, after autonomic blockade (mecamylamine), nebivolol (0.1, 0.3, and 1.0 mg/kg i.v.) right shifted the bolus i.v. isoproterenol tachycardia dose-response curves by dose ratios of 5, 18, and 90 in sham rabbits, respectively, and 5, 11, and 23 in wrap rabbits, respectively, indicating significant cardiac beta 1-adrenoceptor antagonism. In guinea pig isolated right atria pretreated with atropine (1 microM) and desipramine (DMI, 0.1 microM), norepinephrine concentration-response curves were antagonised competitively by nebivolol (3-100 nM), giving a pKb of 7.90. In separate atria without DMI pretreatment, neither nebivolol (100 nM) nor propranolol (100 nM) had any significant effect on the increase in the rate of norepinephrine efflux following electrical field stimulation (0.5-2 Hz, 3 min). These findings suggest that at concentrations of nebivolol that show substantial beta 1-adrenoceptor antagonism, there is no evidence of hypotension or bradycardia nor additional effects on cardiac norepinephrine release. Why nebivolol lowers blood pressure in some species but not in the conscious rabbit is not known.
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PMID:Relationship between the sympatholytic action of nebivolol and hypotension. 138 20

alpha-Immunoreactive inhibin was measured using an enzyme immunoassay kit in the culture medium (Ham's F-10 medium supplemented with 14% heat-inactivated human serum) from day 3 or 4 to day 14 post-fertilization of 31 surplus pre-embryos from eight women participating in an in-vitro fertilization programme. Inhibition secretion was demonstrated in all of them from the fourth day after fertilization (mean +/- SEM: 3.0 +/- 0.7 U) and was independent of the morphological development of pre-embryos (2-4 cells, n = 4; 6-8 cells, n = 4; 8-10 cells, n = 9; 10-12 cells, n = 4; morulae, n = 5 and blastocysts, n = 4). On days 7, 10, 13 and 14 post-fertilization, mean inhibin values +/- SEM for non-disintegrated pre-embryos were respectively: 6.5 +/- 0.9 U, 12.3 +/- 2.0 U, 16.8 +/- 3.2 U and 20.2 +/- 3.7 U; however, when disintegration was noted on days 10 and 13 after fertilization, inhibin mean values were 9.0 +/- 1.4 U and 8.4 +/- 1.7 U respectively. Inhibin levels were significantly correlated with human chorionic gonadotrophin levels in the same culture media only on day 13, while correlation with pregnancy specific beta 1-glycoprotein occurred on day 7 post-fertilization. In conclusion, early human pre-embryos secrete alpha-immunoreactive inhibin before the cytotrophoblast is formed. This secretion increases significantly with time when development is continued, while disintegration is followed by a net decline in the rate of inhibin release.
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PMID:Secretion of alpha-immunoreactive inhibin by human pre-embryos cultured in vitro. 152

We investigated alterations in myocardial beta- and beta 1-adrenergic receptor (BAR and B1AR) number during hyperdynamic state induced by endotoxin or cytokines. [METHODS] Twenty-nine Japanese White rabbits were divided into 2 groups. Hearts were removed 18 h after intraperitoneal administration of sterile saline (SAL) or E. coli endotoxin (LPS; 50 micrograms/kg) (Group E, n = 12), or 3 h after intravenous injection of SAL or cytokines (interleukin 1-beta; 5 micrograms/kg followed by 25 ng/kg/min for 2 h, or tumor necrosis factor; 5 micrograms/kg) (Group C, n = 17). BAR and B1AR numbers were determined in myocardial membranes from rabbit left ventricles with techniques of radioactive ligand binding study. We used [3H] dihydroalprenolol (3H-DHA) as radioactive ligand, and specific 3H-DHA binding to BARs was defined as the difference between the presence and the absence of 10 microM propranolol. B1AR number was assessed through the specific binding of 3H-DHA in the presence of ICI 118, 551 (5 x 10(-8) M), a highly selective beta 2-adrenergic receptor antagonist. In Group E, mean arterial blood pressure (MAP), heart rate (HR), and cardiac output (CO) (by thermodilution) were measured under pentobarbital sodium anesthesia before excision of hearts. [RESULTS] In Group E, CO was significantly (p less than 0.05) increased in rabbits injected with LPS (E-LPS) as compared with that in rabbits injected with SAL (E-SAL) (E-LPS; 0.75 +/- 0.02 l.min-1, E-SAL; 0.61 +/- 0.05 l.min-1, mean +/- SEM). MAP and HR were slightly decreased in E-LPS but not significantly. Maximum binding (Bmax) of 3H-DHA to BARs was significantly (p less than 0.05) decreased by 18% in myocardial membranes from E-LPS compared to E-SAL (E-LPS; 48.2 +/- 4.3 fmol/mg protein, E-SAL; 58.9 +/- 2.9 fmol/mg protein, mean +/- SEM). Similarly, Bmax of 3H-DHA to B1ARs was decreased by 18% in E-LPS, although no statistical significance was detected. In Group C, both BAR and B1 AR number was slightly, but not significantly decreased 3 h after administration of cytokines. [CONCLUSION] These data suggest that down regulation of cardiac BARs may occur during hyperdynamic stage of endotoxic shock.
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PMID:[Alterations in number of rabbit myocardial beta-adrenergic receptors in endotoxic shock: down regulation in hyperdynamic sepsis model and effects of cytokines administration]. 166 39

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

Treatment with beta 1-selective antagonists causes selective sensitization of isolated strips of human atrial myocardium to the inotropic action of epinephrine and beta 2-agonists but not of norepinephrine. To determine whether beta 1-selective antagonist treatment alters the responsiveness of cardiac beta 2-adrenoreceptors in vivo, we measured the positive chronotropic responses to salbutamol injected into the right coronary artery. Ten patients treated with atenolol (50-100 mg daily) were compared with 10 patients not treated with beta-blockers. The mean dose required to cause an increase in heart rate of 30 beats/min was 2.29 micrograms (log dose 0.36 +/- 0.12 micrograms [mean +/- SEM]) in the atenolol-treated patients. In the non-beta-blocker-treated patients, the dose required to cause an increase in heart rate of 30 beats/min was significantly greater, 8.91 micrograms (log dose 0.95 +/- 0.11 micrograms) (p less than 0.005). We conclude that treatment with beta 1-selective beta-blockers leads to increased cardiac responsiveness to beta 2-adrenoreceptor stimulation. This may be the underlying mechanism of the beta-blocker withdrawal syndrome and may make the heart more susceptible to the adverse effects of epinephrine in situations of stress (e.g., myocardial infarction).
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PMID:In vivo demonstration of cardiac beta 2-adrenoreceptor sensitization by beta 1-antagonist treatment. 168 65

Studies with a range of monoclonal and polyclonal antisera to components of the human, rat, and chick vitronectin receptor, alpha V beta 3, and the VLA beta 1 chain show that chick and rat osteoclasts express similar integrin receptors to those described in man. Biochemical analysis with monoclonal antibody 23C6 confirmed the presence on chick osteoclasts of a vitronectin receptor heterodimer of similar size (110/95 kDa reduced) to that immunoprecipitated from human osteoclastoma giant cells. The synthetic peptide GRGDSP, corresponding to the cell adhesion sequence in fibronectin, but not GRGESP peptide, induced significant (P less than 0.005) osteoclast retraction in chick and rat osteoclasts at IC50s (+/- SEM) of 210.0 +/- 14.4 and 191.4 +/- 13.7 microM, respectively; monoclonal anti-vitronectin receptor alpha V beta 3 complex antibody, 23C6, produced similar changes in chick osteoclasts (IC50 = 1.45 +/- 0.22 microM). Antibody 23C6 inhibited the number of pits resorbed in dentine by chick osteoclasts over a concentration range of 4.4 to 88 micrograms/ml; a significant 76% reduction (P = 0.03) was observed at a final concentration of 88 micrograms/ml (6 microM). The effect of peptides upon dentine resorption was less dramatic. No consistent inhibition was seen using chick osteoclasts. Inhibitory effects on resorption by rat osteoclasts were, however, observed; significant reduction in resorption occurred with both GRGDSP (78%; P less than 0.01) and GRGESP (67%; P = 0.02) peptides at 400 microM peptide concentration. These data demonstrate that osteoclast function can be disrupted by low concentrations of the anti-vitronectin receptor antibody, 23C6. The inhibitory effects of the peptides used in this study produced effects on dentine resorption which were generally weaker and variable, although osteoclast cell adhesion was consistently inhibited in an Arg-Gly-Asp (RGD)-dependent manner. We conclude that the vitronectin receptor may play an important role in effecting resorption of mineralized tissues by osteoclasts.
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PMID:Arg-Gly-Asp (RGD) peptides and the anti-vitronectin receptor antibody 23C6 inhibit dentine resorption and cell spreading by osteoclasts. 171 31

To evaluate potential adverse effects of acetate use in hemodialysis (HD), we measured plasma interleukin (IL-1 alpha, IL-1 beta, IL-6), TNF alpha, TGF beta 1, and beta 2-microglobulin levels with ELISA assays in normal (N = 9), CRF (N = 6), CAPD (N = 7) and HD (N = 8) subjects and compared the effects of acetate (Ac) and acetate-free (Ac-free) dialysate. TGF beta 1 was the only cytokine consistently detected. Compared to normals (median 57, range 53 to 68 pg/ml, one undetected; N = 8), TGF beta 1 was higher in the CRF (75, 70 to 97 pg/ml, one undetected) and CAPD (75.5, 66 to 116 pg/ml, N = 6) groups (P less than 0.05), and was somewhat higher in the HD (68, 52 to 88 pg/ml) group (P less than 0.10). Acutely, TGF beta 1 pre-HD (70, 63 to 88 pg/ml) increased above normals post AcHD [79.5, 65 to 140 pg/ml uncorrected for ultrafiltration (UF)] and was higher after AcHD versus Ac-free HD both uncorrected (79.5, 65 to 140 pg/ml vs. 70, 52 to 86 pg/ml) and corrected for UF (68, 51 to 115 pg/ml vs. 57, 43 to 69 pg/ml; P less than 0.05). beta 2-microglobulin was not different after AcHD (81.2 +/- 8.0 mg/ml) versus Ac-free HD (72.5 +/- 6.9 mg/ml). Significantly lower serum inorganic phosphorus was also found four hours post-AcHD compared to four hours post-Ac-free HD (0.87 mmol +/- 0.10 SEM vs. 1.05 mmol +/- 0.07 SEM; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of acetate dialysate on transforming growth factor beta 1, interleukin, and beta 2-microglobulin plasma levels. 176 11

Pulmonary reactivity to methacholine after equipotent beta-blocking doses of propranolol and esmolol was compared in seven basenji-greyhound dogs during thiopental-fentanyl anesthesia. Equipotent doses of esmolol and propranolol were determined by both heart rate effects and by isoproterenol response curves. Propranolol (2 mg/kg) was administered intravenously as a bolus dose and esmolol (0.4-0.5 mg.kg-1.min-1) was administered by continuous infusion. Both esmolol and propranolol significantly decreased heart rate and mean arterial pressure (P less than 0.001). Baseline pulmonary resistance and dynamic compliance did not change after the administration of either propranolol or esmolol. However, propranolol significantly shifted the methacholine dose-response curve to the left so that methacholine (0.3 mg/ml) increased pulmonary resistance by 7.9 +/- 0.97 cmH2O.l-1.s-1 (mean +/- SEM of seven dogs) after pretreatment with propranolol but only 4.4 +/- 0.89 cmH2O.l-1.s-1 (P less than 0.05) without propranolol pretreatment (control). Esmolol, however, did not significantly shift the methacholine dose-response curve. Methacholine (0.3 mg/ml) increased resistance 4.0 +/- 0.89 cmH2O.l-1.s-1 during esmolol administration. This study shows that at equipotent beta 1-blocking doses, propranolol, but not esmolol, produces significant increases in pulmonary reactivity to methacholine.
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PMID:Pulmonary reactivity to methacholine during beta-adrenergic blockade: propranolol versus esmolol. 197 72

Beta blockers inhibit corneal re-epithelialization. This may be due to beta-2 receptor controlled mechanisms. To investigate this possibility we performed a randomized, double-masked study involving 60 rabbit iatrogenic induced corneal ulcers produced with iodine vapour. Two beta specific drug compounds were tested, namely, betaxolol hydrochloride 0.25% (Alcon) (beta 1) and L132-468 (Sandoz, Basel) 0.25% (beta 2), and phosphate-buffered solution (PBS) as control. There was no statistical difference in the wound healing rates among all groups at 24 hours but there were significant differences at 48 hours (p less than 0.01). At 72 hours, the L132-468 treated groups showed significantly less healing than the betaxolol hydrochloride treated group. The PBS-treated group was healed at this time. By 20th post burning day, SEM revealed that betaxolol hydrochloride treated corneas were completely healed with normal epithelial microvilli. The L132-468 treated corneas were also healed but desquamation and abnormal cells were observed. In conclusion, beta-2 blockers inhibit corneal re-epithelialization more potently than beta-1 blockers.
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PMID:Beta adrenoceptors and regenerating corneal epithelium. 197 15


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