Evaluation of inhibitory guanine nucleotide regulatory protein Gi function in hepatocyte and liver membranes from obese Zucker (fa/fa) rats and their lean (Fa/?) littermates.

Previous studies have shown that hepatocyte and liver membranes from insulin resistant animals exhibit an impairment of inhibitory guanine nucleotide binding regulatory protein, Gi function, such that a Gi defect may contribute towards the diabetic syndrome. In the current studies, it is shown that the demonstration of Gi activity in liver and hepatocyte membranes is dependent critically on the membrane preparation technique. A technique is defined that allows functional Gi activity to be demonstrated in liver and hepatocyte membranes from both lean (Fa/?) and obese (fa/fa) Zucker rats. Consequently, previous reports on the loss of Gi function in insulin resistant states require revaluation.