Effects of adrenergic blocking agents on plasma free fatty acid concentrations

Abstract

To blockade tonic sympathetic influences on FFA (free fatty acids) plasma concentrations, or responses by adipose tissue to administered amines, dogs received Dibenzyline, Dibenamine, ergotamine or trimethaphan. Plasma FFA and glucose in femoral vessels and hepatic and portal veins were determined. Estimated hepatic plasma flow (EHPF) and mean blood pressures were recorded. Unanesthetized, untreated dogs often showed FFA responses to injected amines that were quantitatively different from previous testing. FFA responses in anesthetized animals were more reproducible. Dibenzyline elevated FFA and glucose levels and lowered blood pressure. Trimethaphan elevated FFA concentrations and decreased EHPF, glucose and blood pressure. Ergotamine decreased FFA, blood pressure and EHPF. Dibenzyline or Dibenamine failed to block glucose or FFA responses to injected catecholamines, but ergotamine usually decreased hyperglycemic and occasionally FFA responses. Trimethaphan did not prevent FFA or glucose changes in dogs made hypercapnic. Like the hyperglycemic response, FFA release by adipose tissue is difficult to block even with large doses of blocking agents.