心房钠尿肽对大鼠主动脉弓压力感受器活动的影响

EFFECTS OF ATRIAL NATRIURETIC PEPTIDE ON AORTIC BARORECEPTOR ACTIVITY IN RATS

在隔离灌流的大鼠主动脉弓－主动脉神经标本上，观察了心房肽Ⅲ（ａｔｒｉｏｐｅｐｔｉｎⅢ，ＡＰⅢ）对主动脉弓压力感受器活动的影响。主动脉弓内压保持１３．３ｋＰａ条件下向灌流液中加入ＡＰⅢ（２．０μｇ／ｍｌ）后，主动脉神经传入放电较对照值增加６４±２７％（Ｐ＜０．００１）；升降灌流压时，主动脉神经传入放电随之增减，饱和压（ＳＰ）由２２．５±０．５降至２１．３±０．５ｋＰａ（Ｐ＜０．０５），工作范围（ＯＲ）由１２．１±０．４降至１０．６±０．４ｋＰａ（Ｐ＜０．０５），阈压（ＴＰ）无明显变化；压力感受器机能曲线向左上方移位，曲线的最大积分值（ＰＩＶ）由５０８±６６％增至７３０±５２％（Ｐ＜０．０５），曲线最大斜率（ＰＳ）由５５．６±７．５增至９３．２±６．８％·ｋＰａ－１（Ｐ＜０．０５）；冲洗掉ＡＰⅢ后，主动脉神经传入放电基本恢复至对照水平．主动脉弓内压保持在１３．３ｋＰａ条件下，向灌流液中加入硝普钠（ＮＰ，１．０μｇ／ｍｌ），主动脉神经传入放电虽有所减少，但无统计学意义（Ｐ＞０．０５）；升降灌流压时，ＴＰ，ＳＰ，ＯＲ均无明显变化，对压力感受器机能曲线及ＰＳ也无显著影响，而ＰＩＶ由６６７±７８降至５０２±７４％（Ｐ＜?

Effects of atriopeptin Ⅲ (APⅢ) on the aortic baroreceptor activity in rats were studied in the isolated aorta arch-aortic nerve preparation in situ. By perfusing the isolated aortic arch with APⅢ (2. 0 μg/ml) in rats, at constant intra-aortic pressure (IAP)of 13. 3 kPa, the integral of aortic nerve activity (IANA) was increased by 64±27%(P<0. 001), the Stepwise increases and decreases of IAP were correspondingly accompanied by increase and decrease in IANA, while the saturation pressure (SP) and the operating range (OR) of aortic baroreceptor activity were decreased from 22. 5± 0. 5to 21. 3±0. 5 kPa (P<0. 05) and 12. 1± 0. 4 to 10. 6± 0. 4 (P<0. 05), respectively, and the threshold pressure (TP) did not show any changes. The function curve of aortic baroreceptor was shifted to left and upward, and the peak integral value (PIV)and the Peak slope (PS) of the curve were increased from 508±66 to 730±52% (P<0. 05), 55. 6± 7. 5 to 93. 2± 6. 8%·kPa-1 (P<0. 05), respectively. After washing out of AP Ⅲ, the IANA returned to the control level. By perfusing the. aortic arch with sodium nitroprusside (NP, 1. 0μg/ml), at constant intra-aortic pressure (IAP)of 13. 3 kPa, although the IANA was decreased as compared with the control, there was no statistical significance (P>0. 05). There were no changes in TP, SP and OR during stepwise increases and decreases of IAP, the function curve of aortic baroreceptor and PS were not affected by NP, but the PIV was decreased from 667±78 to 502±72% (P<0. 05). Taken together, the results show that the aortic baroreceptor activity was facilitated by APⅢ, an effect which was not attributed to its vasodilating action. It is proposed that the effect of AP Ⅲ on aortic baroreceptor may result from its direct action on the ANP receptors within the area of aortic baroreceptor.