A Role Of Nitric Oxide In The Autonomic Nervous System And Blood Pressure Regulation

Nitric Oxide (NO) is a secondary messenger, whose wide and important physiological and pathological effect has been earned more and more attentions. Recently, the relationship between NO and Autonomic Nervous System (ANS) was paid more and more attention. It was said NO may be involved in modulating ANS' s activities.To study the effect of NO on ANS, in the present study, PE was i. v. administrated to elevate blood pressure, and the effect of NO related drugs, such as sodium nitroprusside (SNP) , L-arginine and Nw-nitro-L-arginine methyl ester (L-NAME) on baroreflex activity were invesgated. Then, the different effects the endogenous and exogenous NO imposed on ANS were assessed. The results demonstrated that NO imposes effect on baroreflex activity, however, the behaviors of exogenous and endogenous NO are different. Endogenous NO may be involved in the regulation of autonomic nervous system via central nervous system or Carotid sinus, and inhibits the baroreflex sensitivity.To quantitatively investigate the direct effect of NO on blood pressure, NO level was changed by i.v. administrating NO substrate ?L-Arg and NOS inhibitor ?L-NAME, and this change in abdominal aorta in SD-rat was detected by NO sensor. The result demonstrated that there are several nano molar NO in blood pressure. L-Arg and L-NAME can modulate blood pressure through NO. Without considering other factors, the ascending or descending of NO derived from endothelium will increase or decrease the blood pressure. However, this change may promote negative feed-back mechanism of ANS, so that the blood pressure will come back or go beyond its original level. In the conclusion, there is a correlation between NO in blood vessel and the blood pressure, but this correlation is not always positive.The present study could be useful for the future studies on the relationship between NO and cardiovascular system function.