The Role of Vasopressin in Reduced Renal Mass-Saline Hypertension

Authors: Besim ÖZAYKAN, Ayşe DOĞAN

Abstract: The cause of reduced renal mass (RRM)-saline hypertension is not clear. In our study, it was aimed to investigate the role of vasopressin (AVP) in this type of hypertension by using selective V 1 antagonist of AVP. RRM was performed in 32 normotensive male Wistar rats under anesthesia in which we used a mixture of ketamine (130 mg/kg, i.m.) and chlorpromazine (1.3 mg/kg, i.m.). After a one-week of recovery period, all of the rats were given a low sodium diet and either distilled water (group 1) or 1% NaCl (group 2) as drinking water for 4 weeks. Five weeks after nephrectomy, indirect blood pressure (BP) and heart rate (HR) measurements were performed. Group 1 was normotensive but group 2 was hypertensive. One day later, AVP antagonist (10µg/kg) or vehicle was intravenously injected to normotensive and hypentensive rats under pentobarbital sodium anesthesia. After injections, BP and HR values were recorded for 30 minutes. The antagonist caused decreases in the mean arterial pressures of both groups which were greater in the hypertensive group (p<0.05). In the normotensive group, HR was increased by the antagonist (p<0.05). No significant diference was present between the two groups with regard to plasma volume and plasma osmolality. Thus, it was concluded that the pressor effect of AVP may have been augmented in RRM-saline hypertension.

Keywords: Hypertension, vasopressin, nephrectomy, sodium intake.

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