Cuabain inhibitable and non-inhibitable glucose uptakes in ventricular slices and diaphragms of rat.

Abstract

Some of insulin-stimulated glucose uptakes in rat tissues were found to be inhibited by ouabain, and the sensitivity to ouabain was altered in diabetic states (Waki.I., Tamura, T. and Kimura, M.: Jpn. J. Pharmacol., 32, 203P,1982). The purpose of the present study was to elucidate some of the properties of the ouabain inhibitable glucose uptake. Male Sprague-Dawley rats 5-8 wk old were sacrificed to measure the glucose uptake in ventricular slices and diaphragms. Anti-heart membrane antibodies(HMAb) were prepared by immunization with a Triton X-100 extract of plasma membrane rich fraction from rat cardiac muscle. HMAb stimulated the glucose uptake in ventricular slices in a dose-dependent fashion. Ouabain (ImM) entirely inhibited the effect of HMAb as well as insulin. When insulin was combined with HMAb, no additive effect on glucose uptake was observed, while the combination of insulin with isoproterenol showed the potentiation. In diaphragms, the effect of HMAb (lmg/ml) as well as ConA (lmg/ml) was partially inhibited by ouabain (ImM) like that seen in the case of insulin and different from that seen in the case of spermidine. HMAb exerted the biological activity after being absorbed with rat erythrocyte ghosts, and never influenced the Na+, K+-ATPase activity. These results suggest that ouabain inhibitable and/or non-inhibitable effector systems played an important role in the stimulation of glucose uptake in ventricular slices and diaphragms of rat.