Growth hormone regulates the distribution of L-type calcium channels in rat adipocyte membranes.

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American journal of physiology. Cell physiology, ISSN: 1522-1563, Vol: 275, Issue: 2, Page: C505-C514

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Gaur, Shikha; Morton, Mary E.; Frick, G. Peter; Goodman, H. Maurice
American Physiological Society
Adipocytes; Adipose Tissue; Animals; Calcium; Calcium Channels; Calcium Channels, L-Type; Cell Membrane; Cells, Cultured; Cytosol; Dihydropyridines; Epididymis; Growth Hormone; Isradipine; Kinetics; Male; Microsomes; Rats; Rats, Inbred Strains; Life Sciences; Medicine and Health Sciences
article description
Earlier studies demonstrated that deprivation of growth hormone (GH) for ≥3 h decreased basal and maximally stimulated cytosolic Ca in rat adipocytes and suggested that membrane Cachannels might be decreased. Measurement of L-type Ca channels in purified plasma membranes by immunoassay or dihydropyridine binding indicated a two- to fourfold decrease after 3 h of incubation without GH. No such decrease was seen in unfractionated adipocyte membrane preparations. The decrease in plasma membrane channel content was largely accounted for by redistribution of channels to a light microsomal membrane fraction. Immunoassay of α-, α/δ-, and β-channel subunits in membrane fractions indicated that the channels redistributed as intact complexes. Addition of GH during the 1st h of incubation prevented channel redistribution, and addition of GH after 3 h restored channel distribution to the GH-replete state of freshly isolated adipocytes. The studies suggest that GH may regulate the abundance of Ca channels in the adipocyte plasma membrane and thereby modulate sensitivity to signals, the expression of which is Cadependent.