Pentosan polysulfate treatment preserves renal autoregulation in ANG II-infused hypertensive rats via normalization of P2X1 receptor activation

Guan Z, Fuller BS, Yamamoto T, Cook AK, Pollock JS, Inscho EW. Pentosan polysulfate treatment preserves renal autoregulation in ANG II-infused hypertensive rats via normalization of P2X(1) receptor activation. Am J Physiol Renal Physiol 298: F1276-F1284, 2010. First published March 3, 2010; doi:10.1152/ajprenal.00743.2009.-Inflammatory factors are elevated in animal and human subjects with hypertension and renal injury. We hypothesized that inflammation contributes to hypertension-induced renal injury by impairing autoregulation and microvascular reactivity to P2X1 receptor activation. Studies were conducted in vitro using the blood-perfused juxtamedullary nephron preparation. Rats receiving ANG II (60 ng/min) infusion were treated with the anti-inflammatory agent pentosan polysulfate (PPS) for 14 days. The magnitude and progression of hypertension were similar in ANG II and ANG II + PPS-treated rats (169 +/- 5 vs. 172 +/- 2 mmHg). Afferent arterioles from control rats exhibited normal autoregulatory behavior with diameter decreasing from 18.4 +/- 1.6 to 11.4 +/- 1.7 mu m when perfusion pressure was increased from 70 to 160 mmHg. In contrast, pressure-mediated vasoconstriction was markedly attenuated in ANG II-treated rats, and diameter remained essentially unchanged over the range of perfusion pressures. However, ANG II-treated rats receiving PPS exhibited normal autoregulatory behavior compared with ANG II alone rats. Arteriolar reactivity to ATP and beta, gamma-methylene ATP was significantly reduced in ANG II hypertensive rats compared with controls. Interestingly, PPS treatment preserved normal reactivity to P2 and P2X(1) receptor agonists despite the persistent hypertension. The maximal vasoconstriction was 79 +/- 3 and 81 +/- 2% of the control diameter for ATP and beta, gamma-methylene ATP, respectively, similar to responses in control rats. PPS treatment significantly reduced alpha-smooth muscle actin staining in afferent arterioles and plasma transforming growth factor-beta 1 concentration in ANG II-treated rats. In conclusion, PPS normalizes autoregulation without altering ANG II-induced hypertension, suggesting that inflammatory processes reduce P2X1 receptor reactivity and thereby impair autoregulatory behavior in ANG II hypertensive rats.