ABSTRACT
AIM: To determine whether argipressin (Arg) plays a role in central neural control of cardiovascular function by acting on the lateral septal nuclei (LSN). METHODS: Measuring mean arterial blood pressure (MAP) and heart rate (HR) responses followed microinjection of Arg into the LSN of rats anesthetized with urethane. RESULTS: Arg (100, 200, and 400 ng) injected into the LSN produced a dose-dependent hypertension and tachycardia. Maximal changes of MAP were 0.9 +/- 0.6, 2.3 +/- 1.3, 4.0 +/- 1.4 kPa, respectively; maximal changes of HR were 12 +/- 27, 50 +/- 33, and 89 +/- 27 bpm, respectively. Pretreatment of the LSN with a vasopressin 1 type antagonist d (CH2)5Tyr(Me) Arg abolished the MAP and HR responses produced by injection of Arg. Peripheral alpha-adrenergic blockade with phentolamine blocked the hypertension responses to injection of Arg into the LSN. CONCLUSION: Arg acts in the region of the LSN to exert a central action on the cardiovascular system that is mediates by stimulation of sympathetic outflow.
Subject(s)
Arginine Vasopressin/pharmacology , Blood Pressure/drug effects , Heart Rate/drug effects , Septal Nuclei/physiology , Vasoconstrictor Agents/pharmacology , Animals , Female , Male , Rats , Rats, Wistar , Septal Nuclei/drug effectsABSTRACT
Graded injections of argipressin (Arg, 150, 300, and 600 ng/1.5 microliters CSF, 2 min) into the medial amygdaloid body in anesthetized rats produced a dose-related increase in the mean arterial pressure and heart rate (Maximal delta MAP = 2.9 +/- 1.5 kPa, Maximal delta HR = 67 +/- 38 bpm), which lasting > 40 min at 600 ng dosage. Naloxone (15 micrograms/15 microliters CSF) injected into the lateral ventricle blocked the cardiovascular responses to Arg. These results suggest that Arg exerts a central action on the cardiovascular system via the opioid in the lateral ventricle.
