Inhibition of prostaglandin F2alpha-induced reflex bradycardia and hypotension by meclofenamic acid.

Intravenous injection of prostaglandin F2alpha (4-15 mug/kg, i.v.) produces an increase in pulmonary arterial pressure in conjunction with reflex bradycardia and hypotension in the anesthetized cat. Meclofenamic acid (30 mg/kg, i.v.) inhibited the bradycardia and the reflex contribution to the systemic hypotension. Neither the PGF2alpha-induced pulmonary vasoconstriction nor the direct systemic vasodilator actions of PGF2alpha were blocked by meclofenamate. In addition, the reflex responses caused by i.v. veratrine and 5-HT were not inhibited by meclofenamate. These results suggest that meclofenamic acid selectively blocks the afferent mechanism by which PGF2alpha induces reflex bradycardia and hypotension in the cat.