Reflex cardiovascular responses originating in exercising muscles of mice

The cardiovascular responses induced by exercise are initiated by two prima ry mechanisms: central command and reflexes originating in exercising muscl es. Although our understanding of cardiovascular responses to exercise in m ice is progressing, a murine model of cardiovascular responses to muscle co ntraction has not been developed. Therefore, the purpose of this study was to characterize the cardiovascular responses to muscular contraction in ane sthetized mice. The results of this study indicate that mice demonstrate si gnificant increases in blood pressure (13.8 +/- 1.9 mmHg) and heart rate 13 3.5 +/- 11.9 beats/min) to muscle contraction in a contraction-intensity-de pendent manner, Mice also demonstrate 23.1 +/- 3.5, 20.9 +/- 4.0, 21.7 +/- 2.6, and 25.8 +/- 3.0 mmHg increases in blood pressure to direct stimulatio n of tibial, peroneal, sural, and sciatic hindlimb somatic nerves, respecti vely. Systemic hypoxia (10% O-2-90% N-2) elicits increases in blood pressur e (11.7 +/- 2.6 mmHg) and heart rate (42.7 +/- 13.9 beats/min), while incre asing arterial pressure with phenylephrine decreases heart rate in a dose-d ependent manner. The results from this study demonstrate the feasibility of using mice to study neural regulation of cardiovascular function during a variety of autonomic stimuli, including exercise-related drives such as mus cle contraction.