Action site of ketanserin enhancing baroreflex function is within the rostral ventrolateral medulla in anesthetized rats.
In our previous studies, it was found that ketanserin enhanced baroreflex sensitivity (BRS) in rats and this effect was not blood pressure dependent. The present work was designed to investigate the effects of ketanserin on BRS within the nucleus tractus solitarus (NTS) and the rostral ventrolateral medulla (RVLM). In anesthetized rats, BRS were evaluated by the changes in depressor action of aortic nerve stimulation and bradycardiac response to rapid pressor action of intravenous phenylephrine. It was found that bilateral injection of ketanserin (250 pmol for each side) into the NTS not only significantly increased blood pressure, but also attenuated baroreflex function. Interestingly, when ketanserin was bilaterally injected into RVLM, a significant enhancement of BRS was found and there were no modifications in basal blood pressure and heart period. The present study demonstrates that ketanserin-induced enhancement of BRS mainly occurred within the RVLM, which might contribute to the systemic effects of ketanserin on BRS.
Fu
Yan-Jun
YJ
Department of Pharmacology, Second Military Medical University, 325 Guo He Road, Shanghai 200433, China.
Wang
Wei-Zhong
WZ
Cai
Guo-Jun
GJ
Wang
Min-Wei
MW
Su
Ding-Feng
DF
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D017704:Baroreflex / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D004558:Electric Stimulation; D006339:Heart Rate / Q000187:drug effects; D007650:Ketanserin / Q000494:pharmacology*; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D010525:Peripheral Nerves / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology
D000316:Adrenergic alpha-Agonists; D000959:Antihypertensive Agents; D010656:Phenylephrine; D007650:Ketanserin