PT  - JOURNAL ARTICLE
AU  - Hawthorn, M H
AU  - Taylor, D A
AU  - Fleming, W W
TI  - Characteristics of adaptive supersensitivity in the left atrium of the guinea pig.
DP  - 1987 May 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 453--457
VI  - 241
IP  - 2
4099  - http://jpet.aspetjournals.org/content/241/2/453.short
4100  - http://jpet.aspetjournals.org/content/241/2/453.full
SO  - J Pharmacol Exp Ther1987 May 01; 241
AB  - Chronic pretreatment of guinea pigs with reserpine (0.1 mg/kg/day for 7 days) induces inotropic supersensitivity in left atria. The sensitivity is increased to isoproterenol, norepinephrine, 5'-guanylylimidodiphosphate and forskolin, and the maximum response is increased to the partial agonist albuterol. These results, coupled with data in the literature, suggest that adaptive supersensitivity in the guinea pig heart is due to a change in one or more of the components of the adenylate cyclase system that is specifically coupled to beta adrenoceptors. The results indicate that the supersensitivity is demonstrable when the concentration-response curves for agonists are determined in isolated whole left atria but not when they are determined in strips cut from left atria. This explains a discrepancy in the literature. It is suggested that cellular changes, possibly in electrolyte distribution, resulting from the additional manipulation of cutting the atria into slices obscure the sensitivity difference between the control and experimental tissues.