Blood Pressure and Indices of Glomerular Filtration Area in Hypertensive and Normotensive Prague Rats

The involvement of the kidney in the pathogenesis of hypertension has long been recognised, although the specific renal mechanisms underlying this phenomenon are still unknown. A current hypothesis attributes hypertension to a reduction in glomerular filtration area by glomerular loss. The present study analyses the relationship between glomerular number and volume and conscious systolic blood pressure (SBP) in 4- to 53-week-old hypertensive (PHR) and normotensive (PNR) rats of the Prague strain. Adult PHRs had higher SBP, were larger and had larger kidneys than PNRs, but 20% fewer glomeruli. A significant negative correlation between SBP and glomerular number was found in PHR males, but not in PHR females or PNRs. There was no correlation at all between glomerular volume and SBP and, in young animals, both SBP and glomerular number were higher in PHRs than in PNRs. In addition, in adult PHRs, glomerular volume and SBP were higher in males than in females. In summary, a generally valid, causal relationship linking raised blood pressure to decreased glomerular number or volume could not be demonstrated in the Prague rat model of genetically determined hypertension. The nature of the renal mechanism(s) determining the hypertension in this model remains unknown.