Histamine-2-receptor blockade does not affect hyperemia after cerebral ischemia in young swine

OBJECTIVETo determine whether histamine-2 (H2) receptor antagonists can blunt the increase in cerebral blood flow after cerebral ischemia. DESIGNProspective, randomized trial. SETTINGAnimal laboratory. SUBJECTSPiglets aged 1 to 2 wks. INTERVENTIONSThree groups of piglets were anesthetized with pentobarbital, mechanically ventilated, and hemodynamically monitored. Each animal was randomized to receive one of three treatments 20 mins before ischemiafamotidine (0.6 mg/kg iv), cimetidine (5 mg/kg iv), or an equivalent volume of saline (3 mL). Ischemia was maintained for 15 mins by tightening ligatures around the brachiocephalic trunk and left subclavian arteries plus the induction of hemorrhagic hypotension (50 nun Hg). Reperfusion was initiated by the reinfusion of shed blood and removal of the ligatures. MEASUREMENTS AND MAIN RESULTSThe three groups were not different with regard to baseline arterial blood gases, cerebral perfusion pressure, microsphere-determined cerebral blood flow, or oxygen consumption (Vo2). Ischemia (cerebral blood flow