Mechanical signals and mechanosensitive modulation of intracellular [Ca²⁺] in smooth muscle

TY - JOUR

T1 - Mechanical signals and mechanosensitive modulation of intracellular [Ca2+] in smooth muscle

AU - An, Steven S.

AU - Hai, Chi Ming

PY - 2000

Y1 - 2000

N2 - We tested the hypothesis that strain is the primary mechanical signal in the mechanosensitive modulation of intracellular Ca2+ concentration ([Ca2+](i)) in airway smooth muscle. We found that [Ca2+](i) was significantly correlated with muscle length during isotonic shortening against 20% isometric force (F(iso)). When the isotonic load was changed to 50% F(iso), data points from the 20 and 50% F(iso) experiments overlapped in the length-[Ca2+](i) relationship. Similarly, data points from the 80% F(iso) experiments clustered near those from the 50% F(iso) experiments. Therefore, despite 2.5- and 4-fold differences in external load, [Ca2+](i) did not deviate much from the length-[Ca2+](i) relation that fitted the 20% F(iso) data. Maximal inhibition of sarcoplasmic reticular (SR) Ca2+ uptake by 10 μM cyclopiazonic acid (CPA) did not significantly change [Ca2+](i) in carbachol-induced isometric contractions and isotonic shortening. CPA also did not significantly change myosin light-chain phosphorylation or force redevelopment when carbachol-activated muscle strips were quickly released from optimal length (Lo) to 0.5 Lo. These results are consistent with the hypothesis and suggest that SR Ca2+ uptake is not the underlying mechanism.

AB - We tested the hypothesis that strain is the primary mechanical signal in the mechanosensitive modulation of intracellular Ca2+ concentration ([Ca2+](i)) in airway smooth muscle. We found that [Ca2+](i) was significantly correlated with muscle length during isotonic shortening against 20% isometric force (F(iso)). When the isotonic load was changed to 50% F(iso), data points from the 20 and 50% F(iso) experiments overlapped in the length-[Ca2+](i) relationship. Similarly, data points from the 80% F(iso) experiments clustered near those from the 50% F(iso) experiments. Therefore, despite 2.5- and 4-fold differences in external load, [Ca2+](i) did not deviate much from the length-[Ca2+](i) relation that fitted the 20% F(iso) data. Maximal inhibition of sarcoplasmic reticular (SR) Ca2+ uptake by 10 μM cyclopiazonic acid (CPA) did not significantly change [Ca2+](i) in carbachol-induced isometric contractions and isotonic shortening. CPA also did not significantly change myosin light-chain phosphorylation or force redevelopment when carbachol-activated muscle strips were quickly released from optimal length (Lo) to 0.5 Lo. These results are consistent with the hypothesis and suggest that SR Ca2+ uptake is not the underlying mechanism.

KW - Acetylcholine

KW - Calcium

KW - Intracellular calcium concentration

KW - Mechanotransduction

KW - Muscle length

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U2 - https://doi.org/10.1152/ajpcell.2000.279.5.c1375

DO - https://doi.org/10.1152/ajpcell.2000.279.5.c1375

M3 - Article

C2 - 11029285

SN - 0002-9513

VL - 279

SP - C1375-C1384

JO - AM.J.PHYSIOL.

JF - AM.J.PHYSIOL.

IS - 5 48-5

ER -