The effects of CGRP on calcium transients of dedifferentiating cultured adult rat cardiomyocytes compared to non-cultured adult cardiomyocytes: possible protective and deleterious results in cardiac function.
CGRP has potent cardiovascular effects but its role in heart failure is unclear. Effects of CGRP on calcium concentrations in fresh adult rat cardiomyocytes, cultured adult cardiomyocytes and neonatal cardiomyocytes were determined by real time fluorescence spectrophotometry. Treatment of cultured adult cardiomyocytes with CGRP resulted in a rapid cessation of beating and a reduction in intracellular calcium. Similar results were obtained in cultured neonatal myocytes. However, rod-shaped adult cardiomyocytes revealed a number of responses; (a) non-beating cells began to beat with increased intracellular calcium; (b) spontaneously beating cells exhibited increased intracellular calcium content and a faster beating rate or (c), myocytes increased their beating rate and became arrhythmic, suggesting that CGRP action on cultured dedifferentiated adult and neonatal myocytes depletes intracellular calcium, whereas in the rod-shaped mature myocytes calcium is retained, pointing to a different mode of action for CGRP on developing and dedifferentiating cardiomyocytes, compared to fully developed cardiomyocytes.
Schiess
Mya C
MC
Department of Neurology, University of Texas Medical School at Houston, Houston, TX 77030, USA.
Poindexter
Brian J
BJ
Brown
Brandon S
BS
Bick
Roger J
RJ
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000737:chemistry / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D002316:Cardiotonic Agents / Q000494:pharmacology; D002320:Cardiovascular Physiological Phenomena; D002454:Cell Differentiation; D002478:Cells, Cultured; D006321:Heart / Q000502:physiology*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D009200:Myocardial Contraction; D009206:Myocardium / Q000473:pathology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D009479:Neuropeptides / Q000737:chemistry; D051381:Rats; D013050:Spectrometry, Fluorescence; D013997:Time Factors
D015220:Calcium Channels; D002316:Cardiotonic Agents; D009479:Neuropeptides; D015544:Inositol 1,4,5-Trisphosphate; D015740:Calcitonin Gene-Related Peptide; D002118:Calcium