Glucose inhibiton of the permeation of chloromercuribenzene-p-sulphonic acid in the plasma membrane of pancreatic beta-cells.

The transport of chloromercuribenzene-p-sulphonic acid (CMBS) was studied in microdissected pancreatic islets of ob/ob mice incubated in Krebs-Ringer bicarbonate medium. Glucose inhibited the islet uptake of CMBS. The initial binding of CMBS to superficial thiol groups was inhibited to a lesser extent than was its further permeation into the interior of the plasma membrane. The non-metabolized glucose analogue 3-0-methyl glucose had no effect on the permeation of CMBS. Whereas mannoheptulose, epinephrine and diazoxide lacked any effect in themselves, they tended to counteract the glucose inhibition of CMBS permeation. The ability of glucose to inhibit CMBS permeation is related to its insulin-releasing action rather than to its membrane transport or further metabolism.