A specific sugar transport mechanism in smooth muscle and its regulation

Abstract

The membrane transport of 3-O-methyl-D-glucose was studied in vitro in a smooth muscle, the detrusor of rat urinary bladder. Transport occurred by facilitated diffusion and showed the same chemical specificity and sensitivity to specific inhibitors as skeletal and cardiac muscle but its insulin sensitivity was smaller. Transport was increased by agents inhibiting the Na⁺ pump and was decreased by agents which increased Na⁺ and K⁺ gradients by apparently stimulating the Na⁺ pump. In accord with a rate limiting role of transport in glucose utilization, similar stimulating and inhibitory effects were seen when CO₂ production from [¹⁴C]glucose was measured.