Faculty Collaboration Database

Intracellular Ca2+ modulation during short exposure to ischemia-mimetic factors in isolated rat ventricular myocytes. Coll Antropol 2009 Dec;33 Suppl 2(0 2):121-6

Date

02/03/2010

Pubmed ID

20120529

Pubmed Central ID

PMC3804278

Scopus ID

2-s2.0-77449142408 (requires institutional sign-in at Scopus site)   1 Citation

Abstract

We investigated the effects of different ischemia-mimetic factors on intracellular Ca2+ concentration ([Ca2+]i). Ventricular myocytes were isolated from adult Wistar rats, and [Ca2+]i was measured using fluorescent indicator fluo-4 AM by confocal microscopy. Intracellular pH was measured using c5-(and-6)-carboxy SNARF-1 AM, a dual emission pH-sensitive ionophore. Myocytes were exposed to hypoxia, extracellular acidosis (pH(o) 6.8), Na-lactate (10 mM), or to combination of those factors for 25 min. Monitoring of [Ca2+]i using fluo-4 AM fluorescent indicator revealed that [Ca2+]i accumulation increased immediately after exposing the cells to Na-lactate and extracellular acidosis, but not during cell exposure to moderate ischemia. Increase in [Ca2+]i during Na-lactate exposure decreased to control levels at the end of exposure period at extracellular pH 7.4, but not at pH 6.8. When combined, Na-lactate and acidosis had an additive effect on [Ca2+]i increase. After removal of solutions, [Ca2+]i continued to rise only when acidosis, hypoxia, and Na-lactate were applied together. Analysis of intracellular pH revealed that treatment of cells by Na-lactate and acidosis caused intracellular acidification, while short ischemia did not significantly change intracellular pH. Our experiments suggest that increase in [Ca2+]i during short hypoxia does not occur if pH(i) does not fall, while extracellular acidosis is required for sustained rise in [Ca2+]i induced by Na-lactate. Comparing to the effect of Na-lactate, extracellular acidosis induced slower [Ca2+]i elevation, accompanied with slower decrease in intracellular pH. These multiple effects of hypoxia, extracellular acidosis, and Na-lactate are likely to cause [Ca2+]i accumulation after the hypoxic stress.

Author List

Pravdić D, Vladić N, Bosnjak ZJ

Author

Zeljko Bosnjak PhD, MS Emeritus Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Acidosis
Animals
Calcium
Cells, Cultured
Extracellular Space
Heart Ventricles
Hydrogen-Ion Concentration
Hypoxia
Male
Myocardial Reperfusion Injury
Myocytes, Cardiac
Rats
Rats, Wistar
Sodium Lactate