[Carbachol effect on kinetics of the alpha1-adrenergic contractile response of the rat vas deferens].
Analysis of the control kinetics of the rat vas deferens contractile response to phenylephrine showed that alpha 1-adrenoceptors mediating the contraction could be in different functional states. In some organs these receptors represented a single pool with Hill coefficient n = 1 (the linear mode of the Scatchard plot), in others--not a single pool, n > 1 (not linear mode of the Scatchard plot). Activation of muscarinic cholinergic receptors by carbachol exerted a stimulating effect on the alpha 1-adrenergic contractile response especially to low adrenomimetic concentrations and the maximum response was increased. The action of cholinomimetic was accompanied by a decrease of Hill coefficient. When the control represented a single pool of alpha 1-adrenoceptors in the presence of carbachol Scatchard plot became biphasic with Hill coefficient n < 1, in addition to the low affinity pool the high affinity appeared. In case of not homogeneous control pool, in the presence of carbachol a single pool was revealed and n was close to 1. These findings suggest that the stimulatory effect of carbachol is caused by its modulator action on the alpha 1-adrenoceptors states and activating influence on the intracellular effector's system.
Berdysheva
L V
LV
Institute of Developmental Biology, Russian Acad. Sci., 26 Vavilov St., Moscow 119334, Russia.
Manukhin
B N
BN
D058646:Adrenergic alpha-1 Receptor Agonists; D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D014649:Vas Deferens / Q000187:drug effects* / Q000502:physiology
D058646:Adrenergic alpha-1 Receptor Agonists; D018721:Muscarinic Agonists; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D002217:Carbachol