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The effects of adrenoceptor agonists and antagonists on plasma potassium concentration in anaesthetized guinea‐pigs, rabbits and rats
Author(s) -
Coats Rachel A.
Publication year - 1985
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1985.tb11104.x
Subject(s) - endocrinology , phentolamine , medicine , propranolol , guinea pig , stimulation , chemistry , agonist , apamin , antagonist , alpha (finance) , in vivo , atenolol , potassium channel , biology , receptor , blood pressure , construct validity , nursing , microbiology and biotechnology , patient satisfaction
1 An intravenous K + ‐sensitive electrode has been used to monitor plasma [K + ] changes induced by α‐ and β‐adrenoceptor agonists in anaesthetized guinea‐pigs, rabbits and rats. The effects of phentolamine and propranolol on these responses were studied. 2 In the guinea‐pig both α‐ and β‐adrenoceptor agonists produced a biphasic response consisting of an initial rapid increase in [K + ] which was followed, within 1 min, by a fall below baseline. The antagonist studies indicated that in this species both phases of the response could be elicited by either α‐or β‐adrenoceptor activation. 3 In the rabbit the responses were both slower and smaller than those seen in the guinea‐pig and required larger agonist doses. In addition it was found that the increase in plasma [K + ] was α‐adrenoceptor‐mediated while the subsequent fall was seen only with β‐adrenoceptor activation. 4 In the rat triphasic changes in plasma [K + ] were seen consisting of an initial decrease which was α‐adrenoceptor‐mediated, followed by an increase and then a second fall which was elicited by β‐adrenoceptor stimulation. The increase in plasma [K + ] was only slightly reduced by either α‐ or β‐adrenoceptor antagonists. 5 Apamin, a toxin from bee venom which blocks Ca 2+ ‐activated K + ‐channels, was found to block the hyperkalaemic phase of the response in the guinea‐pig and rabbit but had no effect in the rat. 6 It is concluded that there are marked species differences in the effects of adrenoceptor agonists on plasma [K + ] in vivo. 1