The sympathomimetic activity of (+/-)-pindolol at beta 1- and beta 2-adrenoceptor sites.
In isolated right atrial and stilboestrol-pretreated uterine preparations from both guinea-pigs and rats, pindolol elicited propranolol-sensitive positive chronotropic and smooth muscle relaxant actions. Although the pD2 values for pindolol (8.4-9.2) and (-)-isoprenaline (ISO, 8.4-8.7) fell within the same range in these preparations, the maximum responses to pindolol were less than 15% of those to the catecholamine. Thus, pindolol did not display any selectivity for agonistic actions at beta 1- or beta 2-adrenoceptors. In uteri taken from progesterone-pretreated rats, the pD2 value for (-)-isoprenaline was 9.5 and that of pindolol 8.5. In these preparations the maximal relaxant effect of pindolol (approximately 50% Emax ISO) was greater than that found in oestrogen-pretreated uteri. Thus, it appears that the maximal response of pindolol in vitro can be related to the pD2 value for (-)-isoprenaline. In anesthetized cats, intravenous pindolol elicited non-beta-adrenoceptor-mediated increases in heart rate and decreases in soleus muscle contractility. The mechanism(s) underlying the latter actions are unknown.
Mian
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D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D005260:Female; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009125:Muscle Relaxants, Central; D009200:Myocardial Contraction / Q000187:drug effects; D010869:Pindolol / Q000494:pharmacology*; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D012110:Reserpine / Q000494:pharmacology; D013566:Sympathomimetics; D014590:Uterine Contraction / Q000187:drug effects
D009125:Muscle Relaxants, Central; D011943:Receptors, Adrenergic, beta; D013566:Sympathomimetics; D011374:Progesterone; D012110:Reserpine; D010869:Pindolol; D007545:Isoproterenol