['To determine whether direct retrograde ice saline infusion in the jugular vein without cardiopulmonary bypass protects rat brains after heatstroke.', 'Randomized, controlled, prospective study.', 'University physiology research laboratory.', 'Sprague-Dawley rats (270-320 g, males).', 'Rats were randomized into three groups and given a) no resuscitation after onset of heat stroke (HS, n = 8); b) ice saline infusion in the femoral vein after onset of heat stroke (HS + F, n = 8); or c) retrograde ice saline infusion in the external jugular vein after onset of heat stroke (HS + J, n = 8). Rats were exposed to an ambient temperature of 43 degrees C after vessel cannulation. Their mean arterial pressure, heart rate, colonic temperature, and brain temperature were continuously recorded. Survival time and brain pathology were checked.', 'Although colonic temperature decreased 0.8-1.0 degrees C 15 mins after heatstroke in all groups, no treatment-related changes in colonic temperature were noted in any group. However, significant changes were observed in brain temperature. Fifteen minutes after heatstroke, brain temperature was 37.6 +/- 0.4 degrees C, 36.1 +/- 0.4 degrees C, and 33.6 +/- 0.8 degrees C in HS, HS + F, and HS + J, respectively. Survival time was 16.1 +/- 2.1, 33.0 +/- 3.8, and >120 mins in these groups, respectively. Neuron damage score was significantly lower in HS + J and without lateralization.'] Does hypothermic retrograde jugular perfusion reduce brain damage in rats with heatstroke?