Modulation of cardiovascular response to dynamic exercise by fastigial nucleus.
Mongrel dogs (n = 34) were used to record the cardiovascular responses during submaximal exercise-tolerance tests (ETT) before and after the placement of lesions in rostral portions of the cerebellar fastigial nucleus (FN). Sterile surgical procedures were used to implant solid-state pressure transducers into the left ventricle or descending aorta (anesthesia 1% halothane in O2) and multipolar stainless steel electrodes into FN (anesthesia alpha-chloralose 115 mg/kg iv). Heart rate (HR), maximal left ventricular systolic pressure ( LVPmax ) and its first derivative ( dLVP /dt), and mean arterial blood pressure (MAP) were recorded during a motorized treadmill ETT. Electrolytic direct-current or radio-frequency lesions were made through the indwelling FN electrodes, and the ETT was repeated following 10-14 days recovery. Two-way analysis of variance (ANOVA), with repeated measures on one, and one-way ANOVA for simple effects indicated a significant reduction in HR and MAP (P less than 0.01) but not LVPmax and dLVP /dt occurred during exercise as a result of rostral FN lesions. Although the trend for reduced LVPmax and dLVP /dt was also evident, a relatively greater decrease in blood pressure occurred in the peripheral vasculature during exercise. It was concluded that FN acts as a modulator of HR and MAP during dynamic exercise because of the observed deficits, and because FN is known to both send efferent projections to medullary vasomotor areas and receive projections from motor cortex and muscle and joint afferents.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001794:Blood Pressure; D002319:Cardiovascular System / Q000294:innervation*; D002529:Cerebellar Nuclei / Q000502:physiology*; D004285:Dogs; D006339:Heart Rate; D009200:Myocardial Contraction; D005082:Physical Exertion; D016276:Ventricular Function