Variation of urinary sulfate in relation to renal arylsulfatase A and B in rat models of hypertension

Abstract

The enzyme arylsulfatase B (ARSB; N‐acetylgalactosamine‐4‐sulfate) removes the sulfate group from the non‐reducing end of the sulfated glycosaminoglycans chondroitin‐4‐sulfate and dermatan sulfate. Recent work in renal epithelial cells in cell culture has demonstrated that ASB activity regulates cellular chondroitin‐4‐sulfate (C4S) and kininogen content and bradykinin release in the spent media. In experiments in salt‐sensitive (SS), salt‐resistant (SR), and spontaneously hypertensive (SHR) rats, measurements of urinary sulfate and bradykinin and cellular arylsulfatase A (ARSA) and arylsulfatase B (ARSB) activity and chondroitin‐4‐sulfate content demonstrate significant relationships. Significant differences in the ARSA and ARSB activity (in nmol/mg protein/hr) were demonstrated between the SS (151 ± 8; 106 ± 10), SR (180 ± 9; 132 ± 10) and SHR (227 ± 10; 161 ± 10) rats, in contrast to no differences in the steroid sulfatase, galactose‐6‐sulfatase, or iduronate‐2‐sulfatase activity. (Iduronate‐2‐sulfatase activity was absent.) Urinary sulfate was highly correlated with the ARSB (r=0.96) and the ARSA (r=0.96) activity. Urinary bradykinin was inversely associated with the C4S (r= −0.88). Since ARSB activity is affected by chloride and phosphate, as well as other anions, and ARSA can remove 3‐sulfate groups from cerebroside sulfate, as well as from sulfated tyrosine residues, the study findings suggest new approaches to mechanisms of blood pressure regulation. VA Merit Review funding