Microinjection of adrenomedullin into rostral ventrolateral medulla increases blood pressure, heart rate and renal sympathetic nerve activity in rats.
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 micromol/L, 200 nl) 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 micromol/L, 200 nl) did not change the effects of AM. (3) L-arginine (100 mg/kg, 0.2 ml, 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.
Ji
Shu-Mei
SM
Department of Physiology, Hebei Medical University, Shijiazhuang 050017.
He
Rui-Rong
RR
D053607:Adrenomedullin / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects*; D007668:Kidney / Q000294:innervation*; D020647:Lateral Thalamic Nuclei / Q000187:drug effects; D008526:Medulla Oblongata / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology
D053607:Adrenomedullin