Studies on equine lipid metabolism. 1. A fluorometric method for the measurement of lipolytic activity in isolated adipocytes of rats and horses

A simple and sensitive method for direct and continuous monitoring of free fatty acid (FFA) release, by measuring the pH-sensitive change in relative fluorescence intensity of seminaphthofluorescein (SNAFL-1(TM)) is described . The method was designed to use a small number of adipocytes isolated from fat pads of rats and biopsy specimens of horses for the detection of decre asing pH in fat cell suspensions caused by released FFA into the incubation medium. Species specific differences of lipolysis were demonstrated when a dipocytes of rats and horses are incubated with stimulators or inhibitors o f lipolysis. Norepinephrine (NE) stimulated lipolysis in fat cells of rats whereas adipocytes of horses showed a measurable release of FFA when concom itantly incubated with NE and adenosine deaminase (ADA) or NE and 8-Phenylt heophylline (8-PT), respectively. The incubation of equine far cells with N E and ADA did nor influence the antilipolytic response to insulin. The meth od described enables micro-scaled in vitro studies on lipolytic activity.