Inhibition of nicotine-induced relaxation of the bovine retractor penis muscle by beta-adrenoceptor antagonists.
The relative potency in inhibiting nicotine-induced relaxation of the bovine retractor penis muscle (BRP) was estimated for the racemates of seven beta-adrenoceptor antagonists, both of the optical isomers of propranolol, and lidocaine. The order of potency of the drugs studied was (+)-propranolol greater than (-)-propranolol greater than propranolol greater than alprenolol greater than metoprolol greater than lidocaine greater than acebutolol greater than pindolol greater than sotalol greater than atenolol. It is concluded that the inhibition of the relaxation was not due to blockade of beta-adrenoceptors but to the nonspecific effects of the beta-adrenoceptor antagonists. It is also concluded that the neurotransmitter(s) which was (were) released from the non-adrenergic non-cholinergic inhibitory nerves in the BRP did not relax the muscle by activating the beta-adrenoceptors. It is suggested that the beta-adrenoceptor antagonists inhibited the release of the inhibitory neurotransmitter(s) by a mechanism which is significantly correlated to their lipophilicity.
Department of Pharmacy, University of Helsinki, Finland.
E
E
Klinge
S
S
Alaranta
R
R
Nissinen
N O
NO
Sjöstrand
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects*; D009538:Nicotine / Q000037:antagonists & inhibitors*; D010413:Penis / Q000187:drug effects* / Q000502:physiology; D011433:Propranolol / Q000494:pharmacology; D012044:Regression Analysis
D000319:Adrenergic beta-Antagonists; D009538:Nicotine; D008012:Lidocaine; D011433:Propranolol