Increased Expression and Activity of Phospholipase C in Renal Arterioles of Young Spontaneously Hypertensive Rats

Background The aims of this study were to document the presence of phospholipase C (PLC) isozymes β1, γ1, and δ1 in freshly isolated renal glomeruli and resistance vessels, to compare their expression and activity to that in aorta, and to contrast values between 6-week-old Wistar-Kyoto (WKY) controls and 6-week-old spontaneously hypertensive rats (SHR) during the developmental phase of genetic hypertension. Methods Aorta, preglomerular arterioles, and glomeruli were isolated from 6-week-old rats using standard techniques. PLC isozyme protein level and activity were determined with Western blot analysis and by measuring inositol 1, 4, 5-trisphosphate (IP3) production, respectively. Results Immunoblots indicate that all three PLC isozymes examined are detectable in freshly isolated preglomerular arterioles, glomeruli, and aorta. Increased levels of PLC-β1, and -δ1 were found in all tested vascular tissues of SHR v WKY. No strain difference was noted for PLC-γ1. The relative abundance for both groups was glomeruli > preglomerular arterioles = aorta. The strain difference in protein expression correlated with increased PLC activity in each vascular bed of SHR. Conclusions Protein levels of PLC-β1 and -δ1 and PLC activity are upregulated in the systemic and renal vasculature in 6-week-old SHR, suggesting a role in exaggerated vascular reactivity during the development of genetic hypertension. A more complete understanding of the physiologic roles of PLC isozymes and their contributions to specific aspects of cellular function should advance our understanding of vascular tone/reactivity and hypertrophy/remodeling in normal and hypertensive states.