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Measurement of Receptor‐Activated Phosphoinositide Turnover in Rat Brain: Nonequivalence of Inositol Phosphate and CDP‐Diacylglycerol Formation
Author(s) -
Heacock Anne M.,
Seguin Edward B.,
Agranoff Bernard W.
Publication year - 1993
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1993.tb03258.x
Subject(s) - diacylglycerol kinase , inositol , inositol phosphate , diglyceride , chemistry , receptor , phosphate , second messenger system , biochemistry , gq alpha subunit , endocrinology , medicine , biology , g protein , signal transduction , protein kinase c , enzyme
Two methods for the measurement of receptor‐activated phosphoinositide turnover were evaluated for their degree of correspondence in slices of rat brain; they involved the Li + ‐dependent accumulations of either [ 3 H]‐inositol‐labeled inositol phosphates or [ 3 H]cytidine‐labeled CDP‐diacylglycerol. In contrast to the expectation that the ratio of these two responses would remain approximately constant, varying degrees of correspondence were obtained. The two extremes are exemplified by carbachol, which elicited large increases in both inositol phosphate and CDP‐diacylglycerol labeling, and endothelin, which gave a robust inositol phosphate response with little or no accumulation of 3 H‐CDP‐diacylglycerol. No instance of the presence of the latter response in the absence of 3 H‐inositol phosphate accumulation was observed. Measurement of 3 H‐CDP‐diacylglycerol accumulation thus may add additional insight into the regulation of phosphoinositide turnover and the complex actions of Li + .