AMOUNT OF G-PROTEIN ALPHA-SUBUNIT IN RAT WHITE ADIPOCYTES - LACK OF DIFFERENCE BETWEEN SUBCUTANEOUS AND VISCERAL FAT

It has been the purpose of this study to examine possible differences in the amount of stimulatory (G(s)) and inhibitory (G(i)) G-protein al pha-subunits (measured with a quantitative enzyme-linked immunosorbent assay in fat cell membrane preparation) between subcutaneous and intr a-abdominal regions in rats. The lipolytic response to isoproterenol a nd the number of beta-adrenergic binding sites were also examined. The se parameters were all evaluated simultaneously in subcutaneous (ingui nal), epididymal and perirenal fat samples collected from six male Spr ague-Dawley rats. The membrane contents of the G(s) and G(i) alpha-sub units were similar in the three depots. Moreover, no difference was fo und among the different regions with regard to isoproterenol-stimulate d glycerol release and beta-adrenoceptor number, expressed per cell nu mber. In conclusion, the present study shows for the first time in rat s that the abundance of inhibitory and stimulatory G-protein alpha-sub units is similar in subcutaneous and in visceral adipocytes. Moreover, the number of beta-adrenoceptors and the lipolytic response to isopro terenol do not show significant variations with the anatomical site. A s the present results are apparently in contrast with those obtained p reviously in human adipocytes, there is a possibility that the differe nt results observed in rat and in human fat cells could be explained b y species differences.