PERMISSIVE ROLE OF PTH ON INTRAMYOCARDIAL ARTERIOLAR WALL THICKENING

Background: Abnormalities in cardiovascular structure e.g. LV hypertro phy and thickening of vessels (elastic and peripheral arteries, veins) are hallmarks of renal failure. Among other hormones parathyroid horm one (PTH) has been shown to affect cardiac function and has also been identified as a permissive factor for the activation of the cardiac in terstitium leading to myocardial fibrosis. The present study was desig ned to examine whether PTH was also permissive for intramyocardial art eriolar wall thickening in an experimental model of renal failure. Mat erial and methods: Sham operated or subtotally nephrectomized rats (SN X) were parathyroidectomized (PTX) and received either saline or rat 1 ,34 PTH by osmotic minipump. After perfusion fixation, intramyocardial arterioles were assessed using stereological techniques (wall thickne ss, wall/lumen ratio, minimal lumen diameter, length density). Results : Wall thickness of intramyocardial arterioles was significantly highe r in SNX than in sham-op controls. SNX-PTX animals receiving solvent d id not differ from sham-op controls while SNX-PTX animals receiving PT H had increased values which were comparable with those of SNX. In add ition, PTH treated animals showed signs of marked vascular smooth-musc le cell and endothelial cell activation. Conclusions: The data suggest that intramyocardial arteriolar wall thickening in experimental renal failure and probable changes of vessel architecture in renal insuffic iency in general are dependent upon the permissive effect of PTH.