Open AccessTRPV1 activation stimulates NKCC1 and increases hydrostatic pressure in the mouse lens
Author(s) -
Mohammad Shahidullah,
Amritlal Mandal,
Richard T. Mathias,
Junyuan Gao,
David Križaj,
Sarah Redmon,
Nicholas A. Delamere
Publication year - 2020
Publication title -
american journal of physiology. cell physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.432
H-Index - 181
eISSN - 1522-1563
pISSN - 0363-6143
DOI - 10.1152/ajpcell.00391.2019
Subject(s) - bumetanide , trpv1 , capsaicin , chemistry , capsazepine , cotransporter , hydrostatic pressure , biophysics , osmotic concentration , transient receptor potential channel , sodium , biochemistry , receptor , biology , physics , organic chemistry , thermodynamics
The porcine lens response to a hyperosmotic stimulus involves an increase in the activity of an ion cotransporter sodium-potassium/two-chloride cotransporter 1 (NKCC1). Recent studies with agonists and antagonists pointed to a mechanism that appears to depend on activation of transient receptor potential vanilloid 1 (TRPV1) ion channels. Here, we compare responses in lenses and cultured lens epithelium obtained from TRPV1 -/- and wild type (WT) mice. Hydrostatic pressure (HP) in lens surface cells was determined using a manometer-coupled microelectrode approach. The TRPV1 agonist capsaicin (100 nM) caused a transient HP increase in WT lenses that peaked after ∼30 min and then returned toward baseline. Capsaicin did not cause a detectable change of HP in TRPV1 -/- lenses. The NKCC inhibitor bumetanide prevented the HP response to capsaicin in WT lenses. Potassium transport was examined by measuring Rb + uptake. Capsaicin increased Rb + uptake in cultured WT lens epithelial cells but not in TRPV1 -/- cells. Bumetanide, A889425, and the Akt inhibitor Akti prevented the Rb + uptake response to capsaicin. The bumetanide-sensitive (NKCC-dependent) component of Rb + uptake more than doubled in response to capsaicin. Capsaicin also elicited rapid (<2 min) NKCC1 phosphorylation in WT but not TRPV1 -/- cells. HP recovery was shown to be absent in TRPV1 -/- lenses exposed to hyperosmotic solution. Bumetanide and Akti prevented HP recovery in WT lenses exposed to hyperosmotic solution. Taken together, responses to capsaicin and hyperosmotic solution point to a functional role for TRPV1 channels in mouse lens. Lack of NKCC1 phosphorylation and Rb + uptake responses in TRPV1 -/- mouse epithelium reinforces the notion that a hyperosmotic challenge causes TRPV1-dependent NKCC1 activation. The results are consistent with a role for the TRPV1-activated signaling pathway leading to NKCC1 stimulation in lens osmotic homeostasis.