Premium
Effect of pH on trout vascular smooth muscle
Author(s) -
Dombkowski Ryan Anthony,
Olson Kenneth R
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a305-b
Subject(s) - contraction (grammar) , extracellular , vascular smooth muscle , chemistry , intracellular ph , biophysics , muscle contraction , medicine , intracellular , depolarization , anatomy , endocrinology , smooth muscle , biology , biochemistry
pH is recognized as a modulator of vascular smooth muscle (VSM) tone in mammalian vessels, but little is known about its effects on fish VSM. We investigated the effects of extracellular (pH o ) and intracellular (pH i ) pH on isolated vessels from rainbow trout. In unstimulated efferent branchial (EBA) and coeliaco‐mesenteric arteries (CMA), and anterior cardinal veins (ACV) increasing pH o from 6.8 to 8.8–9.0 produced a dose‐dependent contraction with an estimated half‐maximal response of 8.0–8.2. pH o interactions with other contractile stimuli were agonist‐specific; more force was developed at low pH o in ligand mediated contractions, whereas depolarization‐mediated contractions were greatest at high pH o . Increasing pH i produced sustained contraction in afferent branchial arteries (ABA) suggesting that these vessels could not restore pH i . NH 4 Cl only transiently contracted EBA and CMA suggesting these vessels readily restore pH i . Increasing pH i in KCl‐contracted EBA produced an additional contraction, whereas ligand‐contracted (thromboxane A 2 analog, U‐46619) EBA relaxed. Reducing pH i (NH 4 Cl washout) transiently contracted resting EBA and CMA. NH 4 Cl washout produced an additional, transient contraction of both KCl‐ and U‐46619‐contracted EBA. These studies suggest that OH − , not H + is the physiologically relevant ion for most pH‐mediated effects on VSM. Supported in part by NSF Grant IBN‐0235223.