Characteristics of monosaccharide permeability in arterial tissue and intestinal smooth muscle; effect of insulin.

Abstract

AbstractMonosaccharide permeability was studied in bovine mesenteric arteries and rabbit intestinal smooth muscle. 14C‐labelled 3–0‐methylglucose was used to study counter‐transport and saturation kinetics. L‐glucose‐1–14C and D‐glucose‐1–14C were used to study substrate stereospecificity. 14C and 3H‐labelled sorbitol were used to estimate the extracellular space. In both bovine mesenteric arteries and smooth muscle from rabbit colon the membrane permeability of mono‐saccharides was characterized by substrate stereospecifici, ty, counter‐transport and saturation kinetics. Monosaccharides were transported down a concentration gradient. These results suggest that monosaccharides penetrate vascular and intestinal smooth muscle cell membranes by facilitated diffusion, In the concentration range 5.6–44.4 mM the distribution of unlabelled glucose in bovine mesenteric arteries corresponded to the distribu, tion of sorbitol‐14C, indicating that the membrane transport of glucose was rate limiting for the glucose metabolism. Insulin (0.1 U/ml) increased to a small degree the membrane transport of 3–0‐methylglucose in bovine mesenteric arteries. Compared with the effect of insulin on monosaccharide transport in skeletal muscle the effects on monosaccharide transport in bovine mesenteric arteries and rabbit colon smooth muscle were very small.