Effects of anesthetics on regional hemodynamics in normovolemic and hemorrhaged rats.

Twenty-nine male Sprague-Dawley rats were divided into four groups based on anesthetic exposure, i.e., awake animals and those receiving anesthesia produced by chloralose-urethan, pentobarbital, or by midcollicular brain stem transsection. Before and after hemorrhage (30% of the estimated blood volume), cardiac output (CO) and regional blood flows were measured by the microsphere method. Arterial blood gases and lactate (L) and pyruvate (P) were also determined. CO and regional blood flows were greatest and the L/P ratio was least in awake animals both before and after hemorrhage. In normovolemic rats, the frequency of altered values (as compared with those in awake animals) was similar for all anesthetic techniques, whereas the CO and regional blood flow responses to hemorrhage were altered less frequently in decerebrated animals. Decerebration may be the preferable procedure if the intent is to produce responses in anesthetized animals similar to those in awake rats. If the intent is to study hemodynamics in a specific organ, the selection of an anesthetic technique should be guided by the individual anesthetic effects on that particular tissue.