Open AccessPostnatal development alters functional compartmentalization of myosin light chain kinase in ovine carotid arteries
Author(s) -
Dane W Sorensen,
Elisha R. Injeti,
Luisa Mejia-Aguilar,
James M. Williams,
William J. Pearce
Publication year - 2021
Publication title -
american journal of physiology. regulatory, integrative and comparative physiology/american journal of physiology. regulatory, integrative, and comparative physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.266
H-Index - 175
eISSN - 1522-1490
pISSN - 0363-6119
DOI - 10.1152/ajpregu.00293.2020
Subject(s) - compartmentalization (fire protection) , myosin light chain kinase , carotid arteries , myosin , microbiology and biotechnology , rho associated protein kinase , immunoglobulin light chain , anatomy , medicine , biology , kinase , chemistry , biochemistry , enzyme , genetics , antibody
The rate-limiting enzyme for vascular contraction, myosin light chain kinase (MLCK), phosphorylates regulatory myosin light chain (MLC 20 ) at rates that appear faster despite lower MLCK abundance in fetal compared with adult arteries. This study explores the hypothesis that greater apparent tissue activity of MLCK in fetal arteries is due to age-dependent differences in intracellular distribution of MLCK in relation to MLC 20 . Under optimal conditions, common carotid artery homogenates from nonpregnant adult female sheep and near-term fetuses exhibited similar values of V max and K m for MLCK. A custom-designed, computer-controlled apparatus enabled electrical stimulation and high-speed freezing of arterial segments at exactly 0, 1, 2, and 3 s, calculation of in situ rates of MLC 20 phosphorylation, and measurement of time-dependent colocalization between MLCK and MLC 20 . The in situ rate of MLC 20 phosphorylation divided by total MLCK abundance averaged to values 147% greater in fetal (1.06 ± 0.28) than adult (0.43 ± 0.08) arteries, which corresponded, respectively, to 43 ± 10% and 31 ± 3% of the V max values measured in homogenates. Confocal colocalization analysis revealed in fetal and adult arteries that 33 ± 6% and 20 ± 5% of total MLCK colocalized with pMLC 20 , and that MLCK activation was greater in periluminal than periadventitial regions over the time course of electrical stimulation in both age groups. Together, these results demonstrate that the catalytic activity of MLCK is similar in fetal and adult arteries, but that the fraction of total MLCK in the functional compartment involved in contraction is significantly greater in fetal than adult arteries.