In:
American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 276, No. 3 ( 1999-03-01), p. H834-H843
Abstract:
Cardiac L-type Ca 2+ channels can be stimulated by activation of β 2 -adrenoceptors. We intended to determine how the gating behavior at the single-channel level (cell-attached configuration) is affected after selective stimulation of β 2 -adrenoceptors. Rat cardiomyocytes were exposed to zinterol, a β 2 -agonist ( n = 7), isoproterenol ( n = 6), a nonselective agonist, 8-bromo-cAMP ( n = 6), and a combination of isoproterenol and ICI-118551 ( n = 8), a selective β 2 -receptor antagonist, or isoproterenol and CGP-20712A, a β 1 -selective antagonist ( n = 7). In all groups the ensemble-average current and the availability of the channels to open on depolarization were increased in a similar fashion. In addition, the open probability ( P o ) within active sweeps was elevated. However, zinterol exerted this effect in a unique manner. It elevated P o not by shortening closed times but solely by reducing active sweeps with very low P o and a short burst duration. All zinterol effects were abolished by ICI-118551 ( n = 5) and mimicked by isoproterenol plus CGP-20712A ( n = 7). We conclude that β 2 -adrenoceptor activation of L-type channels differs qualitatively from the classical cAMP-dependent mechanism.
Type of Medium:
Online Resource
ISSN:
0363-6135
,
1522-1539
DOI:
10.1152/ajpheart.1999.276.3.H834
Language:
English
Publisher:
American Physiological Society
Publication Date:
1999
detail.hit.zdb_id:
1477308-9
SSG:
12
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