The time dependent effects of intravenous sodium meclofenamate (6 mg/kg) on blood flow to a variety of organs was studied in the conscious rabbit. 2. After meclofenamate administration, blood flow was reduced in the kidney and adrenal glands and increased in the hepatic artery. The changes were relatively short lived and had disappeared by 30 min in the kidney and 60 min in the adrenal gland. 3. Cerebral vascular resistance was decreased after meclofenamate in the absence of any change in arterial acid-base balance. 4. A physiological effect of vasodilator prostaglandins on adrenal and splanchnic beds, in addition to the previously reported actions on the kidney, is suggested. Cerebral vasodilation following meclofenamate may indicate a dominant action of vasoconstrictor prostanoids in the brain. 5. The importance of timing of haemodynamic measurements after short term infusions of meclofenamate is demonstrated.
