Magnesium ions control prostaglandin reactivity of venous smooth muscle from spontaneously hypertensive rats.

Prostaglandins (PGs) may play an important role in the pathogenesis of hypertension via their effects on vascular smooth muscle tone. It has been suggested that the capacitance (venous) vessels in the peripheral circulation exhibit an increased tone in the development of hypertension. Recent findings from our laboratory indicate that magnesium ions ([Mg2+]o) play a role in the control of vascular tone, vascular reactivity and Ca2+ content and its distribution in blood vessels. The present study indicates that reactivity of isolated portal venous smooth muscle, obtained from spontaneously hypertensive rats, is markedly reduced in the absence of [Mg2+]o. In addition, our findings indicate that portal venous smooth muscle from age-matched inbred Wistar-Kyoto, but not from normal age-matched Wistar controls, also exhibits decreased responsiveness to PGs in the absence of [Mg2+]o. These new data suggest that Mg2+ may be an important and overlooked factor in the etiology of hypertensive vascular disease.