Interaction between Ca/sup + +/-channel antagonists and. cap alpha. /sub 2/-adrenergic receptors in rabbit ileal cell membrane

Conference · Tue Mar 04 23:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:7189618

Homeidan, F R; Wicks, J; Cusolito, S; El-Sabban, M E; Sharp, G W.G.; Donowitz, M

An interaction between Ca/sup + +/-channel antagonists and the ..cap alpha../sub 2/-adrenergic receptor on active electrolyte transport was demonstrated in rabbit ileum. Clonidine, an ..cap alpha../sub 2/-agonist, stimulated NaCl absorption apparently by Ca/sup + +/-channel antagonism since it inhibited /sup 45/Ca/sup + +/ uptake across the basolateral membrane and decreased total ileal calcium content. This stimulation was inhibited by the Ca/sup + +/-channel antagonists dl- and l-verapamil and cadmium but not by nifedipine. The binding of /sup 3/H-yohimbine, a specific ..cap alpha../sub 2/-adrenergic antagonist, was studied on purified ileal cell membranes using a rapid filtration technique. dl-Verapamil and Cd/sup + +/ inhibited the specific binding of /sup 3/H-yohimbine over the same concentration range in which they affected transport. In contrast, nifedipine had no effect on binding, just as it had no effect on clonidine-stimulated NaCl absorption. These data demonstrate that there is an interaction between Ca/sup + +/-channels and ..cap alpha../sub 2/-adrenergic receptors in ileal basolateral membranes. Some Ca/sup + +/-channel antagonists alter ..cap alpha../sub 2/-adrenergic binding to the receptor and ..cap alpha../sub 2/-agonist binding leads to changes in Ca/sup + +/ entry. A close spatial relationship between the Ca/sup + +/-channel and the ..cap alpha../sub 2/-receptor could explain the data.

• Research Organization: Cornell Univ., Ithaca, NY
• OSTI ID: 7189618
• Report Number(s): CONF-8604222-
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:4; ISSN FEPRA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
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ALKALINE EARTH METAL COMPOUNDS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
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DIGESTIVE SYSTEM
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INTERMEDIATE MASS NUCLEI
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ISOTOPES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MEMBRANES
NUCLEI
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ORGANS
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RADIOISOTOPES
REACTION KINETICS
RECEPTORS
SMALL INTESTINE
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VERTEBRATES