Cerebellar lesions alter autonomic responses to transient isovolaemic changes in arterial pressure in anaesthetized cats

Abstract

In previous studies, bilateral lesions of the rostral fastigial nucleus (rFN) of the cerebellum impaired recovery of mean arterial pressure (MAP) after many forms of hypotension. This study examined effects of cerebellar lesions on baroreflex responses during transient, isovolaemic, non-orthostatic changes in MAP in anaesthetized cats. Bilateral rFN lesions did not alter the rate or extent of fall in MAP induced by nitroprusside, but reduced by 39% the reflex increase in heart rate per unit decrease in pressure (delta HR/delta MAP). Femoral artery resistance remained below control levels. Lesions prolonged the time for 50% MAP recovery after nitroprusside by 93%. During phenylephrine-induced MAP increases, bilateral rFN lesions augmented reflex delta HR/delta MAP by 68%. In intact cats, the reflex decrease in HR after phenylephrine was blocked by electrical stimulation of the rFN, but appeared immediately after stimulation was stopped. Stimulation alone increased both MAP and HR. Propranolol failed to block either the increased HR or the suppression of reflex cardiodeceleration induced by rFN stimulation. Decreases in resting HR after rFN lesions may reflect removal of tonic cerebellar inhibition of cardiac parasympathetic tone. Thus, the cerebellum can influence autonomic output and modify baroreflex sensitivity by augmenting cardiovascular responses mediated by the sympathetic nervous system and inhibiting those mediated by the parasympathetic nervous system.

Lateralized and widespread brain activation during transient blood pressure elevation revealed by magnetic resonance imaging

“…Structures within the cerebellum are usually considered to serve primarily somatomotor control functions; however, major cerebellar participation in cardiovascular control has been described in the past 5 decades (Moruzzi, 1940;Reis and Golanov, 1997), particularly with regard to provocative challenges (e.g., hypotensive hemorrhage) and extreme perturbations of blood pressure (Chen et al, 1994). A number of structures that showed signal changes in response to the pressor challenges (e.g., fastigial region) participate in cardiovascular responses to stimulation or lesion manipulation (Paton and Spyer, 1990).…”

Orthostatic hypotension in acute cerebellar infarction

“…Note the increase in heart rate, suggesting an intact compensatory cardiovagal response. c A follow-up HUT test 2 weeks after symptom onset shows normal BP responses cardiovascular control from the results of animal studies [4,5,7]. Instead, the medial portion of the superior semilunar lobule and tonsil were more commonly damaged in patients with OH than in those without OH.…”

“…However, studies on the role of the cerebellum in regulating BP have been mostly based on the results of experimental animal studies [4][5][6][7][8]. Until now, few studies [9,10] have described OH associated with isolated cerebellar lesion in humans.…”

Sudden infant death while awake

“…In a previous study, we identified aspiration of gastric contents into 10 (14%) of 69 cases of SIDS infants who had not undergone CPR [26]. Sudden death preceded by apnea, bradycardia, and hypotension after pharyngeal contact with gastric aspirate or foreign fluid has been documented in developing lambs [27], and recovery is dependent upon the integrity of cerebellar and other medullary mechanisms that respond to extremes of blood pressure change [28,29]. Antecedent events common in early development, including repeated minimally-hypoxic events, can compromise that integrity [30].…”