Myogenic response, a phenomenon in which resistance size arteries and arterioles swiftly constrict or dilate in
 
response to an acute elevation or reduction, respectively in intravascular pressure is a key component of renal
 
autoregulation mechanisms. Although it is well-established that the renal system is functionally immature in 
 
neonates, mechanisms that regulate neonatal renal blood flow (RBF) remain poorly understood. In this study, 
 
we investigated the hypothesis that members of the transient receptor potential vanilloid (TRPV) channels are 
 
molecular components of renal myogenic constriction in newborns. We show that unlike TRPV1-3, TRPV4 
 
channels are predominantly expressed in neonatal pig ...                                    More
                                                        Myogenic response, a phenomenon in which resistance size arteries and arterioles swiftly constrict or dilate in
 
response to an acute elevation or reduction, respectively in intravascular pressure is a key component of renal
 
autoregulation mechanisms. Although it is well-established that the renal system is functionally immature in 
 
neonates, mechanisms that regulate neonatal renal blood flow (RBF) remain poorly understood. In this study, 
 
we investigated the hypothesis that members of the transient receptor potential vanilloid (TRPV) channels are 
 
molecular components of renal myogenic constriction in newborns. We show that unlike TRPV1-3, TRPV4 
 
channels are predominantly expressed in neonatal pig preglomerular vascular smooth muscle cells (SMCs). 
 
Intracellular Ca2+ ([Ca2+]i) elevation induced by osmotic cell swelling was attenuated by TRPV4, L-type Ca2+, 
 
and stretch-activated Ca2+ channel blockers, but not phospholipase A2 inhibitor. Blockade of TRPV4 channels 
 
reversed steady-state myogenic tone and inhibited pressure-induced membrane depolarization, [Ca2+]i 
 
elevation, and constriction in distal interlobular arteries. A step increase in arterial pressure induced efficient 
 
autoregulation of renal cortical perfusion and total RBF in anesthetized and mechanically ventilated neonatal 
 
pigs. Moreover, intrarenal arterial infusion of TRPV4 channel blockers HC 067047 and RN 1734 attenuated 
 
renal autoregulation in the pigs. These data suggest that renal myogenic autoregulation is functional in 
 
neonates. Our findings also indicate that TRPV4 channels are mechanosensors in neonatal pig preglomerular 
 
vascular SMCs, and contribute to renal myogenic autoregulation