- 作者: 童吉士; 管家仁; 唐嘉良; 曾清俊
- 作者服務機構: 國防醫學院生理及生物物理學科; 國防醫學院藥理學科
- 中文摘要: 自主神經系統和腎素血管張力素系統是一般瞭解之循環在於血壓恆定過程中,短期效應和長期效應的主要控制因素。本實驗中我們進行了兩項研究,首先,我們探討長期阻斷腺?接受器是否導引增強由於一些生理性刺激因素,譬如限鈉進食,所造成的腎素激活反應;其次,我們也探討是否內生性腺?具有限制周邊分泌正腎上腺素,和腎上腺素的能力。本計劃當中實驗動物均採用S-D型雄性大白鼠(250 1 20g)。在第一項研究中我們將鼠區分為正常飲水組(蒸餾水)和咖啡因(0.1%)飲水組兩組。進食正常飼料共計10天之後,全體鼠均改食低鈉飼料(鈉含量0.03%),持續6星期。此後,我們分別測試基礎狀況(進食正常飼料10天),進食低鈉飼料第一週和第六週時兩組鼠,腺?對於血壓和心跳的劑量反應影響。我們也利用放射免疫定量方法側量兩組鼠,血漿中腎素活性。我們更進一步建立鼠自體腎灌流模式,觀察長期阻斷腺昔接受器時腎臟功能的變化。在第二項研究中我們測試了非專一性腺?接受器抑制劑,theophylline,對於腺?抑制麻醉鼠血壓和心跳作用的變化。我們也測試了專一性腺?接受器抑制劑,DPSPX,對於hydralazine激活清醒鼠血漿中正腎上腺素,以及腎上腺素分泌的影響。實驗結果顯示,咖啡因對於進食低鈉鼠腺?降低腎素活性,以及,血壓反應都有拮抗作用,而此拮抗作用明顯發生在進食低鈉後的第一週中。進食低鈉鼠長期使用咖啡因,以阻斷腺?接受器後,並無腎臟功能變化之影響。Theophylline確實具有減弱腺?劑量反應相關性抑制血壓和心跳作用的能力。最後,DPSPX能夠明顯地提昇血漿中兒茶酚胺含量,而此提昇效果則明顯表現於hydralazine注射後的實驗組中。歸納以上的結果,我們認為長期阻斷腺?接受器所導引的增強腎素激活反應並不能夠長久維持。內生性腺?能夠張性抑制周邊兒茶酚胺的分泌作用,而此抑制效果則當於交感神經系統激奮時更為明顯。
- 英文摘要: We explored the hypothesis that chronic blockage of adenosine (Ado) receptors might augment therenin response to sodium restriction. In addition,an ancillary topic has been undertaken to test the hy-pothesis that endogenous Ado would restrain plasma norepinephrine (NE) and epinephrine (E) release.Male Sprague-Dawley rats (250士20 g) were fed with low sodium chow (Na+ 0.03%)and drank eitherdistilled water or caffeine containing water (0.1%). Blood pressures were recorded in the presence of dif-ferent concentrations of Ado. Plasma renin activity was measured at the beginning, 1 week and 6 weeksafter the low sodium diet. An in situ autoperfused rat kidney model was used to examine whether renalfunction was influenced by chronic inhibition of Ado receptors. Furthermore, the effect of theophylline oncardiovascular actions of Ado in anaesthetized rats, and the effect of 1,3-dipropyl-8-(p-sulfophenyl)xanthine(DPSPX) on acute hydralazine induced NE and E release in conscious, unrestrained rats were also deter-mined. Our data showed that the inhibitory effect of Ado on renin activity and blood pressure in saltrestricted rats was attenuated by caffeine at the first week but not at six weeks after institution of the lowsodium diet. Renal function in sodium restricted rats did not change after chronic caffeine consumption.Theophylline attenuated the dose-related inhibitory actions of Ado on blood pressure. Finally, DPSPXsignificantly increased plasma catecholamines, and these effects were much greater in rats treated withhydralazine. We conclude that the augmented renin response is not continued during chronic blockage ofAdo receptors. In addition, endogenous Ado tonically inhibits catecholamine secretion, an effect whichis augmented when the sympathetic system is activated.
- 中文關鍵字: adenosine; renin; catecholamine; caffeine; DPSPX; blood pressure; theophylline.
- 英文關鍵字: --