Somatostatin inhibits urinary cyclic AMP excretion in diabetic rats

Short term (30 min) infusion of cyclic somatostatin (50 microgram/rat), insulin (1 U/rat) or the two together significantly suppressed urinary cyclic AMP excretion in streptozotocin-diabetic rats. While somatostatin tended to increase cyclic GMP excretion, insulin had an opposite effect in diabetic but not in normal rats. It is suggested that somatostatin suppresses cyclic AMP excretion by inhibiting directly adenylate cyclase in liver and perhaps in other organs. The possibility that suppression of urinary cyclic AMP is due to inhibition of glucagon secretion is also considered.