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Microinjection of adrenomedullin into rostral ventrolateral medulla increases blood pressure, heart rate and renal sympathetic nerve activity in rats

Ji Shumei, He Ruirong

Department of Physiology,Hebei Medical University.Shijiazhuang 050017,Hebei

Abstract

The present study was undertaken to examine the effects of microinjection of adrenomedullin (AM) into rostral ventrolateral medulla (RVLM) on mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) in 34 anesthetized Sprague-Dawley rats. The results obtained are as follows. (1) Following microinjection of AM (10 #mu#mol/L, 200nl) into the RVLM, MAP, HR and RSNA were significantly increased from 99.09+-3.32 mmHg, 370.78+-7.84 bpm and 100+-0% to 113.57+-3.64 mmHg (P<0.001), 383.28+-7.38 bpm (P<0.001) and 123.72+-2.74% (P<0.001), respectively. (2) Pretreatment with microinjection of calcitonin gene-related peptide receptor antagonist CGRP8-37 (100 #mu#mol/L, 200nl) did not change the effects of AM. (3) L-arginine (100 mg/kg, 0.2ml, i.v.), an NO precursor, abolished the effects of AM. This study demonstrates that AM acting at the rostral ventrolateral medulla may produce significant cardiovascular responses, the effects are not mediated by CGRP receptor but may be abolished by NO.

Key words: Adrenomedullin;Rostral ventrolateral medulla;Mean arterial pressure;Heart rate;Renal sympathetic nerve;Calcitonin gene-related peptide receptor antagonist;L-arginine

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Citing This Article：

Ji Shumei, He Ruirong. Microinjection of adrenomedullin into rostral ventrolateral medulla increases blood pressure, heart rate and renal sympathetic nerve activity in rats. Acta Physiol Sin 2002; 54 (6): (in Chinese with English abstract).