Addition of glucose (5-20 mM) to rat adipocytes provoked dose-related increases in diacylglycerol, without increasing production of [aH]inositol phosphates. Cytosolic protein kinase C enzyme activity and immunoreactivity decreased within 1-5 min of 5 mM glucose addition, and further over 20 min. Membrane protein kinase C increased stoichiometrically during the first 5 min and then decreased. Higher concentrations (10 and 20 mM) of glucose provoked greater and more rapid decreases of cytosolic and membrane protein kinase C. Our findings suggest that glucose stimulates diacylglycerol production by providing substrate for phosphatidic acid synthesis de novo, and this is associated with translocative activation of protein kinase C.

No abstract