Inhibition of vasoconstriction by frusemide in the rat

1 Mesenteric blood flow was measured in anaesthetized rats with a non‐cannulating electromagnetic flow probe around the superior mesenteric artery. Reductions in blood flow were produced by intravenous bolus injections of angiotensin II (1–300ng) and noradrenaline (3–300ng) before and after the administration of frusemide (5 mg kg−1, i.v.). Loss of volume after frusemide was prevented by either a urinary bladder‐intravenous shunt or replacement of urinary output by intravenous saline. 2 Frusemide administration caused a small increase in baseline blood pressure of 3.2 ± 1.3 mmHg (P