CARDIAC AND RENAL ENDOTHELIN-1 BINDING-SITES IN STREPTOZOTOCIN-INDUCED DIABETIC RATS

The aim of this work was to study cardiac and renal endothelin binding sites during the progression of diabetes. Male Cr1:CD (BR) rats were made diabetic by injection of streptozotocin (STZ, 45 mg kg(-1) i.v.). Only rats with a glycaemia of 500 mg per 100 ml or higher, were used. The hearts were taken at 2, 4 or 6 weeks and kidneys at 2 and 6 weeks , after diabetes induction, for binding studies. In the heart, the num ber of Et-l binding sites was significantly increased 2 weeks after ST Z-induction of diabetes (449+/-13 vs 345+/-18 fmol (mg protein)(-1), i n controls; p<0.05) without modification of K-D value (104+/-5 vs 101/-7 pM). Comparable results were obtained 4 and 6 weeks after STZ-indu ction. In the kidney both the parameters were unchanged at all the tim es tested. In conclusion: a specific increase in cardiac Et-1 binding sites, without change in affinity of the peptide, was found 2, 4 and 6 weeks after diabetes induction; while renal Et-1 binding sites were n ot modified. (C) 1995 The Italian Pharmacological Society.