Inhibition of myocardial crossbridge cycling by hypoxic endothelial cells: A potential mechanism for matching oxygen supply and demand?

Ajay M. Shah, Alexandre Mebazaa, Zhao Kang Yang, Giovanni Cuda, Edward B. Lankford, Chris B. Pepper, Steven J. Sollott, James R. Sellers, James L. Robotham, Edward G. Lakatta

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Previous studies have shown that cardiac endothelial cells release substances that influence myocardial contraction. Since PO2 is an important stimulus that modulates endothelial function, we investigated the effects of acute moderate hypoxia and reoxygenation on the release of cardioactive factors by endothelial cells. Endothelial cells cultured from several vascular beds were superfused with normoxic (equilibrated with room air; PO2 ≃160 mm Hg) or hypoxic (PO2, 40 to 50 mm Hg) physiological buffer solution, and the superfusates were reequilibrated to a PO2 of ≃160 mm Hg and then tested for their effects on various myocardial assays. Endothelial cell viability and buffer ionic composition were unaltered after the superfusion procedures. The superfusates of hypoxic endothelial cells induced rapid, potent, reversible inhibition of isolated cardiac myocyte contraction without reducing cytosolic Ca2+ transients. This activity was not lost after heating (95°C) and was present in low molecular weight (M(r), <500) superfusate fractions. Hypoxic endothelial superfusate reduced unloaded shortening velocity of human skinned soleus muscle fibers. It markedly depressed in vitro actin motility over cardiac myosin and reduced the rate of actin-activated cardiac myosin ATPase activity but had no effect on corresponding smooth muscle myosin assays. Reoxygenation of hypoxic endothelial cells resulted in loss of this inhibitory activity. These data indicate that cultured endothelial cells respond to acute moderate hypoxia by releasing an unidentified substance(s) that inhibits myocardial crossbridge cycling, independent of Ca2+ or other second messenger signaling pathways. Such a mechanism could have important implications for the regulation of oxygen supply-demand balance in the heart and be relevant to conditions such as myocardial hibernation.

Original languageEnglish (US)
Pages (from-to)688-698
Number of pages11
JournalCirculation research
Volume80
Issue number5
DOIs
StatePublished - Jan 1 1997

Fingerprint

Endothelial Cells
Oxygen
Cardiac Myosins
Actins
Buffers
Smooth Muscle Myosins
Myocardial Stunning
Myocardial Contraction
Second Messenger Systems
Myosins
Cardiac Myocytes
Heating
Blood Vessels
Cultured Cells
Cell Survival
Skeletal Muscle
Molecular Weight
Air
Hypoxia

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Shah, Ajay M. ; Mebazaa, Alexandre ; Yang, Zhao Kang ; Cuda, Giovanni ; Lankford, Edward B. ; Pepper, Chris B. ; Sollott, Steven J. ; Sellers, James R. ; Robotham, James L. ; Lakatta, Edward G. / Inhibition of myocardial crossbridge cycling by hypoxic endothelial cells : A potential mechanism for matching oxygen supply and demand?. In: Circulation research. 1997 ; Vol. 80, No. 5. pp. 688-698.
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title = "Inhibition of myocardial crossbridge cycling by hypoxic endothelial cells: A potential mechanism for matching oxygen supply and demand?",
abstract = "Previous studies have shown that cardiac endothelial cells release substances that influence myocardial contraction. Since PO2 is an important stimulus that modulates endothelial function, we investigated the effects of acute moderate hypoxia and reoxygenation on the release of cardioactive factors by endothelial cells. Endothelial cells cultured from several vascular beds were superfused with normoxic (equilibrated with room air; PO2 ≃160 mm Hg) or hypoxic (PO2, 40 to 50 mm Hg) physiological buffer solution, and the superfusates were reequilibrated to a PO2 of ≃160 mm Hg and then tested for their effects on various myocardial assays. Endothelial cell viability and buffer ionic composition were unaltered after the superfusion procedures. The superfusates of hypoxic endothelial cells induced rapid, potent, reversible inhibition of isolated cardiac myocyte contraction without reducing cytosolic Ca2+ transients. This activity was not lost after heating (95°C) and was present in low molecular weight (M(r), <500) superfusate fractions. Hypoxic endothelial superfusate reduced unloaded shortening velocity of human skinned soleus muscle fibers. It markedly depressed in vitro actin motility over cardiac myosin and reduced the rate of actin-activated cardiac myosin ATPase activity but had no effect on corresponding smooth muscle myosin assays. Reoxygenation of hypoxic endothelial cells resulted in loss of this inhibitory activity. These data indicate that cultured endothelial cells respond to acute moderate hypoxia by releasing an unidentified substance(s) that inhibits myocardial crossbridge cycling, independent of Ca2+ or other second messenger signaling pathways. Such a mechanism could have important implications for the regulation of oxygen supply-demand balance in the heart and be relevant to conditions such as myocardial hibernation.",
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Shah, AM, Mebazaa, A, Yang, ZK, Cuda, G, Lankford, EB, Pepper, CB, Sollott, SJ, Sellers, JR, Robotham, JL & Lakatta, EG 1997, 'Inhibition of myocardial crossbridge cycling by hypoxic endothelial cells: A potential mechanism for matching oxygen supply and demand?', Circulation research, vol. 80, no. 5, pp. 688-698. https://doi.org/10.1161/01.RES.80.5.688

Inhibition of myocardial crossbridge cycling by hypoxic endothelial cells : A potential mechanism for matching oxygen supply and demand? / Shah, Ajay M.; Mebazaa, Alexandre; Yang, Zhao Kang; Cuda, Giovanni; Lankford, Edward B.; Pepper, Chris B.; Sollott, Steven J.; Sellers, James R.; Robotham, James L.; Lakatta, Edward G.

In: Circulation research, Vol. 80, No. 5, 01.01.1997, p. 688-698.

Research output: Contribution to journalArticle

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T1 - Inhibition of myocardial crossbridge cycling by hypoxic endothelial cells

T2 - A potential mechanism for matching oxygen supply and demand?

AU - Shah, Ajay M.

AU - Mebazaa, Alexandre

AU - Yang, Zhao Kang

AU - Cuda, Giovanni

AU - Lankford, Edward B.

AU - Pepper, Chris B.

AU - Sollott, Steven J.

AU - Sellers, James R.

AU - Robotham, James L.

AU - Lakatta, Edward G.

PY - 1997/1/1

Y1 - 1997/1/1

N2 - Previous studies have shown that cardiac endothelial cells release substances that influence myocardial contraction. Since PO2 is an important stimulus that modulates endothelial function, we investigated the effects of acute moderate hypoxia and reoxygenation on the release of cardioactive factors by endothelial cells. Endothelial cells cultured from several vascular beds were superfused with normoxic (equilibrated with room air; PO2 ≃160 mm Hg) or hypoxic (PO2, 40 to 50 mm Hg) physiological buffer solution, and the superfusates were reequilibrated to a PO2 of ≃160 mm Hg and then tested for their effects on various myocardial assays. Endothelial cell viability and buffer ionic composition were unaltered after the superfusion procedures. The superfusates of hypoxic endothelial cells induced rapid, potent, reversible inhibition of isolated cardiac myocyte contraction without reducing cytosolic Ca2+ transients. This activity was not lost after heating (95°C) and was present in low molecular weight (M(r), <500) superfusate fractions. Hypoxic endothelial superfusate reduced unloaded shortening velocity of human skinned soleus muscle fibers. It markedly depressed in vitro actin motility over cardiac myosin and reduced the rate of actin-activated cardiac myosin ATPase activity but had no effect on corresponding smooth muscle myosin assays. Reoxygenation of hypoxic endothelial cells resulted in loss of this inhibitory activity. These data indicate that cultured endothelial cells respond to acute moderate hypoxia by releasing an unidentified substance(s) that inhibits myocardial crossbridge cycling, independent of Ca2+ or other second messenger signaling pathways. Such a mechanism could have important implications for the regulation of oxygen supply-demand balance in the heart and be relevant to conditions such as myocardial hibernation.

AB - Previous studies have shown that cardiac endothelial cells release substances that influence myocardial contraction. Since PO2 is an important stimulus that modulates endothelial function, we investigated the effects of acute moderate hypoxia and reoxygenation on the release of cardioactive factors by endothelial cells. Endothelial cells cultured from several vascular beds were superfused with normoxic (equilibrated with room air; PO2 ≃160 mm Hg) or hypoxic (PO2, 40 to 50 mm Hg) physiological buffer solution, and the superfusates were reequilibrated to a PO2 of ≃160 mm Hg and then tested for their effects on various myocardial assays. Endothelial cell viability and buffer ionic composition were unaltered after the superfusion procedures. The superfusates of hypoxic endothelial cells induced rapid, potent, reversible inhibition of isolated cardiac myocyte contraction without reducing cytosolic Ca2+ transients. This activity was not lost after heating (95°C) and was present in low molecular weight (M(r), <500) superfusate fractions. Hypoxic endothelial superfusate reduced unloaded shortening velocity of human skinned soleus muscle fibers. It markedly depressed in vitro actin motility over cardiac myosin and reduced the rate of actin-activated cardiac myosin ATPase activity but had no effect on corresponding smooth muscle myosin assays. Reoxygenation of hypoxic endothelial cells resulted in loss of this inhibitory activity. These data indicate that cultured endothelial cells respond to acute moderate hypoxia by releasing an unidentified substance(s) that inhibits myocardial crossbridge cycling, independent of Ca2+ or other second messenger signaling pathways. Such a mechanism could have important implications for the regulation of oxygen supply-demand balance in the heart and be relevant to conditions such as myocardial hibernation.

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