Sex-specific vascular responses to TRPV4 knockout in sugen/hypoxia-induced pulmonary hypertension

Aim: Transient Receptor Potential Vanilloid 4 (TRPV4) is a mechanosensitive, calcium-permeable ion channel expressed in pulmonary endothelial and smooth muscle cells, where it contributes to shear sensing, vasodilation, and cytoskeletal regulation. TRPV4 activity is altered in pulmonary arterial hypertension (PAH), and its expression and signaling are upregulated in disease. PAH is also sexually dimorphic, with females developing PAH more frequently and males exhibiting worse outcomes. This study aims to determine whether a TRPV4 loss-of-function mutation attenuates vascular changes associated with PAH and whether its effects differ between males and females under baseline and Sugen/Hypoxia (SuHx) conditions. Methods: Pulmonary arteries were collected from 17–22-week-old wild-type and TRPV4-mutant male and female rats under normoxia or after SuHx exposure. Passive mechanical properties were measured using tensile testing. Endothelial-dependent relaxation was assessed by wire myography using acetylcholine with and without indomethacin to determine COX contributions, and smooth muscle dependent relaxation was measured using sodium nitroprusside. Protein expression of prostanoid and nitric oxide signaling pathways was evaluated by Western blot. Results: At baseline, wild-type females exhibited greater arterial stiffness than males. The TRPV4 mutation did not change stiffness in males but reduced stiffness in females, eliminating baseline sex differences. After SuHx, the mutation did not significantly alter stiffness in either sex, though opposite trends emerged: mutant males showed slightly increased stiffness and mutant females showed a modest decrease compared with WT. Endothelial-dependent relaxation displayed sex-specific patterns. In controls, TRPV4-mutant males were similar to WT but trended toward reduced acetylcholine-mediated dilation, while females showed no genotype differences and no indomethacin effect. In SuHx WT animals, indomethacin reduced acetylcholine-mediated relaxation as expected. TRPV4-mutant males exhibited a reverse trend, with indomethacin slightly improving relaxation, whereas mutant females showed no detectable indomethacin response. Sodium nitroprusside relaxation was unchanged at baseline between the genotypes and showed only a slight reduction in SuHx mutant males. Western blots showed that COX2 expression increased with SuHx in both sexes regardless of genotype, and the phospho-eNOS:eNOS ratio was reduced by SuHx in males and females with no effect of the TRPV4 mutation. In contrast, COX1 expression increased with SuHx in wild-type animals but not in TRPV4-mutant rats, with SuHx WT trending higher than SuHx TRPV4 mutants in both sexes. Conclusion: TRPV4 knockout does not attenuate SuHx-induced vascular changes but reveals clear sex-specific differences in mechanical properties and endothelial signaling. The mutation selectively reduced stiffness in females at baseline and produced opposing mechanical and COX-related functional trends between sexes under SuHx. Western blot findings further showed that TRPV4 mutation blunted the SuHx-induced increase in COX1 expression. Because this study used a germline TRPV4 loss-of-function model, developmental compensations may mask the role of TRPV4 in adult pulmonary vasculature. Future studies using sex-stratified pharmacological inhibition or inducible adult-onset TRPV4 knockdown are needed to clarify TRPV4’s mechanistic role in PAH and its potential sex-dependent therapeutic relevance. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.