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Pressor responsiveness to vasopressin in spontaneously hypertensive rats

100%

Stepniakowski K., Lapinski M., Januszewicz A., Noszczyk B., Szczepanska-Sadowska E.

Acta Physiologica Polonica

1989

tom 40

nr 2

Stępniakowski, K., Łapiński, М., Januszewicz, A. Noszczyk, В. and Szcze- pańska-Sadowska, E.: Pressor responsiveness to vasopressin in spontaneously hypertensive rats. Acta physiol, pol., 1989, 40 (2): 171-182, The present study was designed to find out whether pressor responsiveness to vasopressin (AVP) is altered in spontaneously hypertensive rats (SHR) in comparison with their normotensiye controls (WKY). Blood pressure and heart rate changes after injection of graded doses of 2.5, 5.0 and 10.0 ng of AVP (Calbiochem) i.v. were compared in 9 conscibus, unrestrained spontaneously hypertensive (SHR) and 11 normotensive Wistar Kyoto (WKY) rats, chronically instrumented with venous and arterial catheters. The threshold dose necessary to elicit a significant increase in blood pressure and reduction of heart rate was lower in WKY than in SHR. At each dose level the blood pressure elevation persisted for a longer period in WKY than in SHR. Bradycardia was greater in WKY than in SHR both in absolute terms and in relation to the blood pressure increase. Thus, the results reveal diminished pressor responsiveness to moderate doses of AVP in SHR in spite of suppressed reflex bradycardia. It is suggested that the peripheral action of AVP on the vascular system is attenuated in SHR.

Effect of vasopressin and V1 receptors blockade on hypotensive action of ANP in normotensive [WKY] and spontaneously hypertensive rats

100%

Lapinski M., Stepniakowski K., Januszewicz A., Noszczyk B., Szczepanska-Sadowska E.

Journal of Physiology and Pharmacology

1992

tom 43

nr 1

The aim of the study was to find out whether vasopressin (AVP) modifies hypotensive and heart rate accelerating effects of atrial natriuretic peptide (ANP) in normotensive (WKY) and spontaneously hypertensive (SHR) conscious rats. The effect of i. v. administration of 1; 2 and 4 µg of ANP on blood pressure (MP) and heart rate (HR) was compared during i. v. infusion of 0.9% NaCl (NaCl), NaCl + AVP (1.2 ng kg⁻¹ min⁻¹) and NaCl + dEt₂ AVP (V₁ receptors antagonist, 0.5 µg kg⁻¹ min⁻¹). AVP increased MP in SHR and WKY and decreased HR in SHR. V₁ antagonist decreased MP and increased HR only in SHR. In SHR ANP decreased MP and increased HR during NaCl, AVP and V₁ antagonist infusion. In WKY these effects were observed only during AVP administration. In each experimental situation hypotension and tachycardia induced by ANP were greater in SHR than in WKY. In both strains ANP induced changes in MP and HR were enhanced during AVP in comparison to NaCl infusion. V₁ antagonist did not modify effects of ANP in WKY and SHR. The results indicate that ANP abolishes hypertensive response induced by blood AVP elevation and that the basal levels of endogenous vasopressin acting through V₁ receptors does not interfere with hypotensive action of ANP neither in WKY nor in SHR.

Ograniczanie wyników

1 Acta Physiologica Polonica

1 Journal of Physiology and Pharmacology

2 Januszewicz A.

2 Lapinski M.

2 Noszczyk B.

2 Stepniakowski K.

2 Szczepanska-Sadowska E.

1 1992

1 1989

Wyniki wyszukiwania

Pressor responsiveness to vasopressin in spontaneously hypertensive rats

Effect of vasopressin and V1 receptors blockade on hypotensive action of ANP in normotensive [WKY] and spontaneously hypertensive rats