Energetic cost of activation processes during contraction of swine arterial smooth muscle

The Journal of Physiology
C J WingardR A Murphy

Abstract

1. The objective of this study was to partition the increase in ATP consumption during contraction of swine carotid arterial smooth muscle estimated from suprabasal oxygen consumption (suprabasal JO2) and lactate release (Jlactate) into a component associated with cross-bridge cycling (JX) and one reflecting activation (JA). 2. Two experimental approaches-varying length under constant activation, and varying activation at a long length (1.8 times the optimal length for force development (Lo)) where force generation is minimal-revealed a linear dependence of JO2 and activation energy (JA) on cross-bridge phosphorylation. Protocols inducing a large increase in myosin regulatory light chain (MRLC) phosphorylation at 1.8 Lo resulted in significant elevations of JO2 and marked reductions in the economy of force maintenance. Our evidence suggests that this is primarily due to the increased cost of cross-bridge phosphorylation. 3. The extrapolated estimate of JA during maximal K(+)-induced depolarization made by varying length was 16%, while at 1.8 Lo it was 33% of the suprabasal JO2 at Lo. Calculated activation energies ranged from 17 to 45% of the suprabasal JO2 at Lo and from 72 to 87% of the suprabasal JO2 at 1.8 Lo under stimulat...Continue Reading

References

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Citations

Apr 25, 2013·The Journal of Physiology·Bhupal P BhetwalBrian A Perrino
Jan 15, 1999·Acta Physiologica Scandinavica·T M Butler, M J Siegman
Feb 8, 2006·American Journal of Physiology. Heart and Circulatory Physiology·Shaojie HanPaul H Ratz
Sep 25, 2001·Journal of Applied Physiology·P KomalavilasC M Brophy
Sep 14, 1999·The American Journal of Physiology·D A WoodrumH Rasmussen
Feb 9, 2000·American Journal of Physiology. Cell Physiology·P R TerritoR S Balaban

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