Sex differences in autoregulation of juxtamedullary glomerular blood flow in hydronephrotic rats

Abstract

The technique of the split hydronephrotic kidney of anesthetized Wistar rats was used for the first time to study afferent and efferent arterioles of juxtamedullary (JM) glomeruli in vivo and to compare their behavior with that of the cortical glomeruli in female (F, 270 g body wt) and male (M, 400 g body wt) rats. The mean length of cortical efferent arterioles (F, 260; M, 380 microns) was less than 10% the length of JM efferent arterioles. Luminal diameters of the JM afferent arteriole (F, 17.1; M, 18.3 microns) and efferent arteriole (F, 25; M, 33.4 microns) were much larger than those of cortical arterioles (afferent: F, 9.1, M, 10.5 microns; efferent: F and M, 11.1 microns). In the hydronephrotic kidney, cortical glomerular blood flow (F, 17.5; M, 18.3 nl/min) is much reduced compared with the normal filtering kidney. This, however, is not true of JM glomerular blood flow (F, 120; M, 262 nl/min). During the reduction of renal perfusion pressure in females blood flow was autoregulated in cortical glomeruli within the pressure range of 110 to 80 mmHg; JM glomeruli failed to show any autoregulation. In males the glomerular blood flow was similarly autoregulated down to 90 mmHg in both cortical and JM nephrons. Local application of indomethacin to the kidneys from female rats reduced the glomerular flow rates by 30% but changed the autoregulatory behavior of cortical and JM glomerular blood flow so that it resembled that observed in untreated males. The data suggest that in females the autoregulatory response, particularly in JM glomeruli, is modified by prostaglandins.

Sex differences in pressure diuresis/natriuresis in rabbits

“…There is also evidence for sex differences in the intrarenal haemodynamic responses to alterations in RAP. Thus, while outer cortical blood¯ow is well autoregulated in both male and female anaesthetized rats, blood¯ow in the outer medulla (Parekh et al 1993) and in juxtamedullary glomeruli (Steinhausen et al 1990) is poorly autoregulated in females relative to males. This sex difference was abolished by cyclooxygenase blockade.…”

“…Thus, while outer cortical blood flow is well autoregulated in both male and female anaesthetized rats, blood flow in the outer medulla ( Parekh et al . 1993 ) and in juxtamedullary glomeruli ( Steinhausen et al . 1990 ) is poorly autoregulated in females relative to males.…”

“…Information from the rat studies cited above ( Munger & Baylis 1988; Munger & Blantz 1990, Steinhausen et al . 1990 , Parekh et al .…”

Renal arteriolar diameters in spontaneously hypertensive rats. Vascular cast study.

“…This assumption is consistent with a study 9 using an isolated, juxtamedullary nephron preparation in which juxtamedullary nephrons sufficiently autoregulate glomerular pressure. A recent report 31 using hydronephrotic kidney showed that male rats' juxtamedullary arterioles have autoregulation but that female rats' juxtamedullary arterioles do not.…”

Renal Autoregulation in Health and Disease

“…Sex differences have been noted in the control of blood perfusion within the kidney by COX metabolites (1152,1412). Blood flow autoregulation in cortical and outer medullary regions of kidneys of male rats was efficient and independent of PGs, whereas poor medullary autoregulation in female rats was attributed to overproduction of PGs.…”