Oct 15, 1992

Positive and negative inotropic effects of carbachol on the embryonic chick atrium

Experientia
L L Protas

Abstract

The effect of carbachol on twitch tension of atrial preparations from chick embryos of different incubation ages (3-14 days) was studied. At every age carbachol evoked negative (at low concentrations) and positive (at higher concentrations) inotropic responses. Maximal response values for both effects increased with age; in 3- and 5-day atria the positive inotropic response prevailed. The muscarinic antagonist pirenzepine inhibited the positive (on 5-day atria) and negative (on strips of 14-day atria) inotropic effects of carbachol with pA2 values of 6.8 and 8.0, respectively, suggesting that muscarinic receptors mediating these effects belong to different receptor subtypes.

Mentioned in this Paper

Embryo
Myocardial Contraction
Cholinergic Muscarinic Antagonist [EPC]
Carboptic
Right Atrial Structure
Chick Embryo
Entire Atrium
Heart
Heart Atrium
Muscle Twitch

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