Abstract MP45: Deletion Of The Transient Receptor Vanilloid-1 (TRPV1) Channel In Rats Attenuates 2 Kidney 1 Clip Hypertension

Abstract

Renal denervation lowers arterial blood pressure (ABP) in both clinical populations and multiple experimental models of hypertension. This therapeutic effect is partly attributed to the removal of overactive renal sensory nerves that increase sympathetic efferent activity and ABP. Renal sensory nerves highly express TRPV1 channels, and administration of the TRPV1 agonist capsaicin increases renal sensory nerve activity. However, the extent by which TRPV1 channels directly contribute to renal nerve dependent models of hypertension has not been tested. To test this hypothesis, we generated a novel TRPV1 -/- rat using CRISPR/Cas9 and deletion of exon 3. Male and female TRPV1 -/- and wild-type littermates (8-12 weeks) were instrumented with telemetry. At 2 weeks later, renovascular hypertension via renal stenosis was produced by placement of a PTFE cuff (0.16 x 0.22 inches, 1mm long) around the right renal artery. Male TRPV1 -/- and wild-type rats had no differences in baseline mean ABP (99±2 vs 98±3 mmHg, respectively; n=7-9) or heart rate (390±7 vs 400±8 bpm, respectively). Renal stenosis significantly increased mean ABP in both groups; however, mean ABP was significantly lower at Day 28 in male TRPV1 -/- versus wild-type rats (125±8 vs 155±2 mmHg, respectively: P<0.01). Ganglionic blockade with chlorisondamine (2.5mg/kg, sc) at Day 28 produced a smaller fall in mean ABP of male TRPV1 -/- versus wild-type rats (-53±4 vs -86±3 mmHg, respectively; P<0.001). On the other hand, female TRPV1 -/- and wild-type rats had no differences in baseline mean ABP (102±2 vs 104±1 mmHg, respectively; n=6-9) or heart rate (419±8 vs 410±7 bpm, respectively). Renal stenosis significantly increased mean ABP in both groups; however, there were no differences at Day 28 between female TRPV1 -/- versus wild-type rats (117±8 vs 122±6 mmHg, respectively). Moreover, the increase in mean ABP was smaller in females versus males. The ganglionic blocker chlorisondamine produced similar depressor responses in female TRPV1 -/- versus wild-type rats (-64±7 vs -65±7 mmHg, respectively). These findings illustrate a sex difference in renovascular hypertension in rats, but importantly indicate that TRPV1 channels contribute to the established phase of renovascular hypertension in male rats.