Growth hormone increases phosphoinositide turnover in rat adipocytes that are sensitive to the insulin-like action of the hormone.

UNLABELLED: The effect of pituitary human growth hormone (hGH) on the 32P-labelling of phosphoinositides and phosphatidic acid was studied in noradrenaline-stimulated rat adipocytes which were either responsive or non-responsive to the antilipolytic (insulin-like) effect of hGH. In cells responsive to the insulin-like effect of hGH, hormone treatment resulted in a marked increase of the 32P-labelling of phosphatidic acid and phosphatidyl inositol in the plasma membrane, high density microsomal, and low density microsomal fractions. The increased 32P-labelling most likely reflects an activation of phosphoinositide phospholipase C. ABBREVIATIONS: IP3 - Myo-Inositol 1,4,5-Triphosphate. BSA - Bovine Serum Albumin, HEPES - N-2-Hydroxyethylpiperazine-N'-2-Ethanesulphonic Acid, hGH - Human Pituitary Growth Hormone, LPC-Lysophosphatidylcholine, LPE - Lysophosphatidylethanolamine, LPI - Lysophosphatidylinositol, PA - Phosphatidic Acid, PC - Phosphatidylcholine, PE - Phosphatidylethanolamine, PI - Phosphatidylinositol, PIP - Phosphatidylinositol-4-Phosphate, PIP2-Phosphatidylinositol-4,5-Diphosphate, PS-Phosphatidylserine.