THE PHYSIOLOGICAL SIGNIFICANCE OF THE SECRETION OF ENDOGENOUS INSULIN INTO THE PORTAL CIRCULATION. III. EVIDENCE FOR A DIRECT IMMEDIATE EFFECT OF INSULIN ON THE BALANCE OF GLUCOSE ACROSS THE LIVER*†

Abstract

There is at present general agreement, based upon abundant in vitro and in tvvo experimental evidence, that insulin exerts an immediate and profound effect on glucose utilization by muscle and adipose tissue (1-5). On the other hand, a direct hepatic action of insulin is disclaimed by most investigators since innumerable studies both in vitro and in vivo have failed to demonstrate clearly a consistent and reproducible effect of insulin upon hepatic glucose metabolism (5-12).