title: The median preoptic area in cardiovascular reflex activity.
abstract: Two examples are used to illustrate the flexibility within the central servocontrol system that regulates blood volume and blood pressure. The variations are seen in the modification of components directed both towards short-term and long-term control. The preferential circuit used in the servocontrol system can and does change. The interaction of baromechanisms with cerebellar-fastigial activation selectively engages sympathetic output to the kidney resulting in an enhanced release of renin that is disproportional to the rise in renal vascular resistance. The cerebellar component adds a feature to the reduction in vascular conductance that when fully developed increases vascular volume. The permissive role of sites in the anteroventral hypothalamus suggests a neural loop that, when absent, not only allows the sympathetic activity to run unabated but fails to prevent a tachycardia state or to develop a bradycardia in response to a rise in arterial pressure. The latter may be a transient feature not persisting for more than a day. However, when compared to the normal responses of the paired sham controls, such a change is taken as an example of dynamic shift in preferential pathways.
mesh_terms: D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001794:Blood Pressure; D001810:Blood Volume; D001933:Brain Stem / Q000502:physiology; D002346:Carotid Sinus / Q000294:innervation; D002415:Cats; D002529:Cerebellar Nuclei / Q000502:physiology; D004558:Electric Stimulation; D007031:Hypothalamus / Q000502:physiology; D007668:Kidney / Q000294:innervation; D011301:Preoptic Area / Q000502:physiology*; D011311:Pressoreceptors / Q000502:physiology; D051381:Rats; D012018:Reflex / Q000502:physiology*; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System; D013564:Sympathetic Nervous System / Q000502:physiology
chemical_list: D012083:Renin