ACUTE EXERCISE AND CARDIOVASCULAR-RESPONSES TO STRESS IN RATS

The purpose of this study was to determine if acute exercise (EX) reduces the cardiovascular response to air jet stress (AJS) in rats. Male Sprague-Dawley rats (n = 11) were instrumented with Doppler Row probes and a carotid arterial catheter to determine mean arterial pressure (MAP), heart rate (HR), mesenteric blood flow (MesBF), and iliac blood how (IliBF). Rats participated in two trials (random order, separated by 48 h): 1) nonexercise (NONEX; 90-min rest on treadmill, 20-min restraint, and 20-min AJS), and 2) exercise (EX; 60-min rest on treadmill, 30-min EX at 20 m/min, 20-min restraint, and 20-min AJS). Increases in MAP (EX = 11 +/- 2%; NONEX = 21 +/- 2%) and HR (EX = 22 +/- 4%; NONEX = 33 +/- 3%) in response to the AJS protocol (restraint + AJS) were significantly less after EX compared to NONEX. Furthermore, decreases in MesBF (EX = -12 +/- 7%; NONEX = -29 +/- 8%) and increases in IliBF (EX = 29 +/- 16%; NONEX = 56 +/- 9%) produced by combined restraint + AJS were significantly less after exercise. Interestingly, the effects of exercise were most, evident in response to the mild restraint required for AJS. The results suggest that acute EX reduces the cardiovascular responses to an AJS protocol (restraint + AJS) in normotensive rats.