Role of TRPV4 in superficial cervical lymphatic vessel contractile function

Abstract

Listen

Translate article

Collecting cervical lymphatic vessels pump lymph and macromolecules drained by brain meningeal lymphatics to the cervical lymph nodes. Collecting lymphatics vessels rely on spontaneous contractions to propel lymph against a pressure gradient to re-enter the venous circulation. The calcium permeable transient receptor potential vanilloid 4 channel (TRPV4) has been shown to mediate intraluminal pressure-induced vasodilatory responses in small arteries. However, whether TRPV4 participates in pressure-dependent contractile responses in lymphatic vessels remains unclear. We hypothesized that increases in intraluminal pressure leads to TRPV4-dependent increases in lymphatic pump function. TRPV4 expression was assessed by PCR assay in isolated superficial cervical lymphatic vessels (sCLV). Using pressure myography, contractile function of isolated sCLV was assessed in the presence of TRPV4 antagonist (1μM HC-067047) or vehicle (DMSO). To quantify lymphatic pump function (FPF), the product of contractile frequency (FREQ) and ejection fraction (EF) was analyzed using repeated end-diastolic and end-systolic diameter measurements. We detected TRPV4 mRNA expression following PCR amplification from isolated sCLV tissue of young C57Bl/6J mice (4-6 months). In pressurized sCLV, TRPV4 activation with GSK 1016790A (10 nM) abolished spontaneous rhythm contractions by causing a sustained constriction, consequently leading to a significant decrease in lymphatic pump function (FPF: 4.67±0.58 vs 1.17±0.86, Vehicle vs GSK 1016790A, n=8, p<0.05) at baseline intraluminal pressure (3 cm H2O). TRPV4 antagonism (HC-067047, 1 μM) did not affect basal sCLV contractility (FPF: 5.15±0.6 vs 3.44±0.43, Vehicle vs HC 067047, n=5, p>0.05). Further, when HC-067047 was applied to the bath and intraluminal pressure was maintained at 2 cm H2O, no changes were observed in FREQ (9.3±1.4 vs 11.7±1.3 Hz, Vehicle vs. HC-067047, n=7 / 9, p>0.05), EF (0.253±0.040 vs 0.268±0.037, Vehicle vs. HC-067047, n=7 / 9, p>0.05), or contractile amplitude (22.54±6.769 vs 26.76±3.028 μm, Vehicle vs HC-067047, n=7 / 9, p>0.05). Similarly, TRPV4 blockade did not alter FREQ (12.4±1.3 vs 14.3±1.4 Hz, Vehicle vs. HC-067047, n=7 / 9, p>0.05), EF (0.090±0.024 vs 0.092±0.019, Vehicle vs HC-067047) or contractile amplitude (7.98±2.814 vehicle vs 9.27±1.88 μm, Vehicle vs HC-067047) at the higher intraluminal pressure of 7 cm H2O. Collectively, these data suggest that TRPV4 channels are not involved in pressure-dependent contractile responses of sCLV in mice, despite inducing a robust constriction upon pharmacological activation. National Institutes of Health (R01 AG073230) and the Alzheimer's Association (AARGD-21-850835) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.