Influence of beta-adrenoceptor blocking agents on the turnover rate of cardiac and splenic noradrenaline in rats.
1 The effects of (+) and (+/-)-propranolol, pindolol, alprenolol, practolol, acebutolol and bretylium were studied on the turnover rate of noradrenaline in heart and spleen of rats. 2 Bretylium (8 mg/kg) greatly reduced the turnover rate of noradrenaline in both organs. 3 (+)-Propranolol (4 and 10 mg/kg) also diminished the turnover rate of noradrenaline, but its effects were smaller than those of (+/-)-propranolol (4 and 10 mg/kg). 4 Pindolol (300 micrograms/kg) greatly increased the turnover rate of noradrenaline; this effect was especially important in the spleen. 5 Alprenolol (4 and 10 mg/kg) acebutolol (20 and 40 mg/kg) practolol (10 mg/kg) did not produce any significant change. 6 These effects are compatible with the view that beta-adrenoceptor blocking agents may affect noradrenaline release in different manners: anaesthetic properties of some of these drugs and blockade of beta 2 prejunctional adrenoceptors produce a diminished release of transmitter, whereas the intrinsic sympathomimetic action of pindolol causes the opposite effect.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D013154:Spleen / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; D009638:Norepinephrine