Sustained contractile force regulated by rho-kinase and protein kinase C in sheep carotid arterial smooth muscle

Leanne C M Smit; Lu Wang; Pasquale Chitano; Chun Y Seow

doi:10.1152/japplphysiol.00592.2022

Sustained contractile force regulated by rho-kinase and protein kinase C in sheep carotid arterial smooth muscle

J Appl Physiol (1985). 2023 Jan 1;134(1):152-159. doi: 10.1152/japplphysiol.00592.2022. Epub 2022 Dec 15.

Authors

Leanne C M Smit^{1

2}, Lu Wang¹, Pasquale Chitano¹, Chun Y Seow^{1

3}

Affiliations

¹ UBC Centre for Heart Lung Innovation, University of British Columbia, Vancouver, Canada.
² Graduate School of Life Sciences, Utrecht University, Utrecht, The Netherlands.
³ Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.

PMID: 36519569
DOI: 10.1152/japplphysiol.00592.2022

Abstract

The time course of smooth muscle contraction can be divided into two phases, the initial phase is associated with force development, whereas the sustained phase is associated with force maintenance. Cumulative evidence suggests that the two phases are regulated by different signaling pathways and that ρ-kinase (ROCK) and protein kinase C (PKC) play an important role in regulating isometric force in sustained contractions. Since the maintenance of sustained force is critical to the function of vascular smooth muscle, unraveling the complex mechanism of force maintenance is crucial for understanding the cell biology of the muscle. The present study examined the effects of ROCK and PKC on the level of phosphorylation of the 20-kD myosin light chain (MLC20) and isometric force during a sustained contraction. We used partial activation and inhibition of ROCK and PKC to reduce the isometric force by 50% of the maximal isometric force in fully activated muscle, F_max. We then examined the level of MLC20 phosphorylation in each case. We found that in partially activated muscle the level of MLC20 phosphorylation required to maintain 50% F_max was much lower than that required in muscles where 50% reduction in F_max was achieved by partial inhibition of ROCK and PKC. The results can be explained by a model containing a contractile apparatus and a cytoskeletal scaffold where force generated by the contractile apparatus is transmitted to the extracellular domain through the cytoskeleton. The results indicate that ROCK and PKC play an important role in force transmission through the cytoskeleton.NEW & NOTEWORTHY The study supports a model that the maintenance of sustained force during a contraction of arterial smooth muscle is dependent on the intracellular transmission of force through the cytoskeleton and that ρ-kinase and protein kinase C plays an important role in the regulation of cytoskeletal integrity and its efficiency in force transmission.

Keywords: GF109203X; H1152; myosin light chain phosphorylation; partial activation; vascular smooth muscle.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Carotid Arteries / metabolism
Muscle Contraction / physiology
Muscle, Smooth, Vascular / metabolism
Phosphorylation
Protein Kinase C* / metabolism
Sheep
rho-Associated Kinases* / metabolism

Substances

Protein Kinase C
rho-Associated Kinases

Grants and funding

CIHR/Canada