Possible involvement of nitric oxide in the central salt-loading-induced cardiovascular responses in conscious rats.
The objective of this study was to elucidate the possible involvement of nitric oxide (NO) in the cardiovascular responses induced by central salt loading. Direct perfusion of the hypothalamic paraventricular nucleus (PVN) region with hypertonic saline (0.3 or 0.45 M) was performed in conscious rats by using an in vivo brain microdialysis technique. The extracellular concentration of NO metabolites in the PVN region was measured, as were the blood pressure (BP) and heart rate (HR). Perfusion of 0.45 M saline increased the BP, HR, and NO metabolite levels in the PVN region; however, perfusion of 0.3 M saline enhanced only the level of NO metabolites but did not induce changes in the BP and HR. Next, we determined whether the NO was involved in the cardiovascular responses induced by hypertonic saline. Pretreatment with N(G)-methyl-L-arginine (L-NMMA), an inhibitor of NO synthase, attenuated the increases in the BP and HR induced by direct perfusion of 0.45 M saline, while direct infusion of 3-morpholinosyndnonimine (SIN-1, a NO donor) in the PVN region induced increases in the BP and HR. These results suggest that local perfusion of the PVN region with hypertonic saline elicits a local release of NO, which may be carried out by activating nitric oxide synthase to produce cardiovascular responses.
Jin
Qing-Hua
QH
Department of Physiology, Yabian University College of Medicine, Yanji, 133000, Jilin, China.
Kunitake
Takato
T
Chu
Chun-Ping
CP
Qiu
De-Lai
DL
Kato
Kazuo
K
Ishizuka
Yuta
Y
Kannan
Hiroshi
H
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D008297:Male; D017551:Microdialysis; D008981:Molsidomine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D012462:Saline Solution, Hypertonic; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; C002385:linsidomine; D008981:Molsidomine; D019001:Nitric Oxide Synthase