Reflex cardiovascular response to brief abdominal visceral ischemia is mediated in part by prostaglandins

Abstract

Prostaglandin concentrations are elevated in intestinal lymph during brief abdominal visceral ischemia, and exogenously applied prostaglandins can directly stimulate or sensitize ischemically sensitive visceral sympathetic nerve fibers. However, it is not known if prostaglandin production during abdominal ischemia is sufficient to contribute to the reflex cardiovascular response (e.g., hypertension). Accordingly, in anesthetized cats, the femoral artery was cannulated for measurement of arterial blood pressure, and the superior mesenteric and celiac arteries were isolated and fitted with snare occluders. After dual occlusion of these arteries (≤20 min), the cyclooxygenase inhibitors indomethacin (10–20 mg/kg iv, n = 5, group 1) or acetylsalicylic acid [50 mg/kg iv ( n = 6) and ia ( n = 2); group 2] were administered and ischemia was repeated. In group 1, indomethacin lowered the reflex arterial blood pressure increment by 39% from 31 ± 7 to 19 ± 5 mmHg ( P > 0.05). In group 2, acetylsalicylic acid significantly ( P < 0.05) reduced the reflex rise in blood pressure by 46% (28 ± 3 to 15 ± 4 mmHg). A second, more invasive preparation ( group 3) was utilized to 1) minimize the confounding, transient, nonreflex rise in blood pressure associated with arterial ligation, and 2) further assess the inhibitory effect of indomethacin. In group 3, the ischemia-induced blood pressure rise of 28 ± 6 mmHg was reduced by 43% to 16 ± 4 mmHg after indomethacin ( n = 4, P < 0.05). Thus blockade of the cyclooxygenase pathway by two structurally dissimilar inhibitors attenuated the visceral-cardiovascular reflex response to brief ischemia, suggesting that prostaglandins released during visceral ischemia contribute significantly to the activation of the reflex cardiovascular response.