The role of central vasopressin V2 receptors in cardiovascular homeostasis

Abstract

The role of central vasopressin V2 receptors in cardiovascular homeostasis It is well established that vasopressin modulates neurogenic control of the circulation both centrally and peripherally. However the exact mechanism is still unexplored. To investigate whether central V2 receptors modulate the neurogenic control of the circulation, we studied the effects of centrally injected selective V2 antagonist on hemodynamic parameters: blood pressure (BP), heart rate (HR) and their variability, under baseline physiological conditions and during stress. We also investigated the effects of over-expression of V2 receptors in the paraventricular nucelus of the hypothalamus on cardiovascular hemodynamic under baseline conditions. BP and HR were assessed by direct recording via indwelling catheter in femoral artery or by radiotelemetric probe inserted in abdominal aorta. Neurogenic control of the circulation was assessed by spectral methodology. Under baseline physiological conditons V2 antagonist didn't modify the level of BP and HR and increased the very low frequency variability of BP. Over-expression of V2 receptors in the paraventricular nucleus increased sympathetically mediated, low-frequency oscillation of BP and HR. Exposure of rats to air-jet stress increased BP, HR and their sympahtetically mediated low-frequency variability and respiration-induced high-frequency variability. Rats pre-treated with the V2 antagonist and exposed to stress exhibited lower BP increase and lower increase od BP variability, as well as shorter recovery time. It follows that vasopressin by the stimulation of central V2 receptors influence the cardiorespiratory response to stress.