The effect of cigarette smoke and diabetes mellitus on muscarinic stimulation of prostacyclin synthesis by the rat penis

The effect of cigarette smoke extracts and experimental diabetes on rat penile prostacyclin (PGI₂) synthesis was investigated. Cigarette smoke extracts induced a dose-related inhibition of methacholine-stimulated PGI₂ secretion. Induction of diabetes by streptozotocin resulted in diminished PGI₂ secretion, which was further inhibited by cigarette smoke extracts in additive fashion. Treatment with insulin prevented the inhibition of PGI₂ in diabetic animals. Since PGI₂ is a potent vasodilator, it may mediate the increased blood flow to the penis responsible for erection following parasympathetic stimulation. The inhibition of PGI₂ secretion by cigarette smoke extracts or diabetes, or both, may therefore provide a mechanism to account for the epidemiological observation that smoking and diabetes are major risk factors for male impotence.