Effects of Norepinephrine and Angiotensin II on the Determinants of Glomerular Ultrafiltration and Proximal Tubule Fluid Reabsorption in the Rat
Effects of Norepinephrine and Angiotensin II on the Determinants of Glomerular Ultrafiltration and Proximal Tubule Fluid Reabsorption in the Rat
复制标题
去甲肾上腺素和血管紧张素II对大鼠肾小球超滤和近端小管液体重吸收决定因素的影响
作者：
B. Myers;W. Deen;B. Brenner
在26只具有表面肾小球的Wistar大鼠中，在静脉输注去甲肾上腺素或血管紧张素II之前和期间研究了肾小球超滤和近端重吸收物的管周毛细血管摄取的决定因素。无论肾灌注压（AP）是否被允许增加，这两种激素产生的升高，由于肾小球血浆流量下降，在肾单位肾小球滤过率变化不大的单肾单位滤过分数。由此导致的输出小动脉压±E的大幅增加伴随着平均肾小球跨毛细血管液压差±ΔP的同等增加。±E和±ΔP相等，表示在输注任一激素之前和期间获得的滤过压平衡。对于这两种激素，当允许±ΔP升高时，通过单个输入和输出小动脉的血流阻力发生显著和大致成比例的增加，而当±ΔP的增加被部分主动脉收缩阻止时，阻力增加主要局限于输出小动脉。尽管-±E显著增加，但平均而言，近端小管液体重吸收的绝对速率未受这些激素的影响，这是由于传出小动脉血浆流速显著降低的相反作用，以及在较小程度上，小管周围毛细血管液压的增加。
In 26 Wistar rats with surface glomeruli, the determinants of glomerular ultrafiltration and peritubular capillary uptake of proximal reabsorbate were studied before and during intravenous infusions of norepinephrine or angiotensin II. Regardless of whether renal perfusion pressure (AP) was permitted to increase, both hormones produced elevations in single nephron filtration fraction due to declines in glomerular plasma flow with little change in nephron glomerular filtration rate. The resulting large increases in the efferent arteriolar oncotic pressure, ±E, were accompanied by equivalent increases in the mean glomerular transcapillary hydraulic pressure difference, ±ΔP. Equality of ±E, and ±ΔP, denoting filtration pressure equilibrium, obtained before and during infusion of either hormone. For both hormones, when elevations in ±ΔP were allowed, marked and roughly proportional increases in the resistance to blood flow through single afferent and efferent arterioles occurred, whereas when increases in ±ΔP were prevented by partial aortic constriction increases in resistance were confined primarily to the efferent arteriole. Despite the marked increases in -±E, absolute rates of proximal tubule fluid reabsorption, on the average, were unchanged by these hormones due to the opposing effects of marked decreases in efferent arteriolar plasma flow rate and, to a lesser extent, increases in peritubular capillary hydraulic pressure.