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Atrial natriuretic factor enhances vasopressin‐induced bradycardia in normotensive (WKY) but not in spontaneously hypertensive (SHR) rats
Author(s) -
LAPIŃSKI M.,
STEPNIAKOWSKI K.,
JANUSZEWICZ A.,
NOSZCZYK B.,
SZCZEPAŃSKASADOWSKA EWA
Publication year - 1988
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1988.tb01269.x
Subject(s) - medicine , vasopressin , endocrinology , bradycardia , blood pressure , heart rate , reflex bradycardia , reflex
. Effect of elevation of blood atrial natriuretic peptide (rat 1–28 ANF) level on pressor responses and bradycardia elicited by vasopressin (AVP) was compared in conscious normotensive (WKY) and spontaneously hypertensive (SHR) rats 14–16 weeks old, instrumented with arterial and venous catheters 1–2 days prior to the experiment. Blood pressure and heart rate were determined before and after i.v. injection of 2·5, 5·0 and 10·0 ng of AVP under control conditions (infusion of saline) and during infusion of ANF at a rate of 0·3 μg kg ‐1 min ‐1 . Administration of ANF did not influence pressor responsiveness to AVP (determined as a maximum increase of systolic blood pressure) neither in WKY nor in SHR, however, it elongated the pressor response to the lowest dose of AVP in WKY. Atrial natriuretic factor significantly enhanced bradycardic responsiveness to AVP (determined as a maximum decrease of HR) in WKY but not in SHR. Reduction of heart rate in relation to the corresponding elevation of the systolic pressure (ΔHR/ΔSP) was also significantly greater in WKY but not in SHR. This effect was significant when blood pressure increases elicited by AVP did not exceed 40 mmHg. The results suggest that ANF potentiates reflex bradycardia elicited by AVP. This action may be a mechanism buffering blood pressure increases in response to AVP. Absence of this effect in SHR may be related to the impairment of the reflex control of blood pressure in this strain.