Abstract
Isoproterenol brings about a rapid transient relaxation of depolarized ileal smooth muscle as well as a longer lasting decline in tension. Only the latter effect is mimicked by dibutyryl cyclic AMP or by phosphodiesterase inhibitors. Beta adrenergic blocking agents cause a rapid transient contraction in preparations relaxed by isoproterenol but not in preparations relaxed by the other agents, and this effect persists when influx of Ca2+ from the extracellular space is prevented. The transient component of the isoproterenol-induced relaxation is therefore attributed to sequestration of Ca2+ at intracellular sites, and the contraction which follows the subsequent addition of beta blocking agents is due to release of Ca2+ from these sites.
Original language | English (US) |
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Pages (from-to) | 2299-2305 |
Number of pages | 7 |
Journal | Life Sciences |
Volume | 23 |
Issue number | 23 |
DOIs | |
State | Published - Dec 4 1978 |
ASJC Scopus subject areas
- General Pharmacology, Toxicology and Pharmaceutics
- General Biochemistry, Genetics and Molecular Biology