Influence of bradykinin upon insulin-insulin receptor interaction in muscular tissue of a rat in vivo, in normo-and hypothermia
Edyta Mądry, Teresa Torlińska, Paweł Maćkowiak, Magdalena Perz, Tomasz Hryniewiecki, Danuta Rutkowska
Med Sci Monit 1998; 4(3): BR408-412
The aim of this study was the influence of bradykinin on insulin-insulin receptor interaction in the rats muscle tissue under normal conditions or in hypothermia.The ability to bindinsulin with insulin receptors in skeletal muscles was evaluated by means of: Specific bindings (Bsp); binding volume of low and high insulin affinity towards insulin receptors (HAIR, LAIR); dissociation and association of complex hormone receptor constants. We calculated the products of constant association and total binding capacity (Ka1xR and Ka2xR) for low and high insulin affinity receptors. We observed a decrease in insulin plasma concentration levels in hypothermic rats as compared to normal conditions. The maximum binding volume of LAIR receptors in hypothermic rats increased, but their affinity towards insulin decreased. The administration of bradykinin to normothermic rats caused a decrease in glucose levels and, an increase in binding volume of LAIR receptors. No affinity of the hormone-receptor complex were noted. In hypothermic conditions, following the administration of bradykinin, inspite of an increase in insulin levels, we did not observe an insulin-receptor response. Conclusions: Bradykinin causes hypoglycemia without influencing the insulin-insulin receptor ineraction. The hypoglycemic effect can be linked to insulin secretion changes at the pancreas level (B islets), which does not exclude its postreceptor activity.
Keywords: insulin receptor, Hypothermia, muscle tissue, Insulin, bradykinin