Evidence of intercellular coupling between co-cultured adult rabbit ventricular myocytes and myofibroblasts

Chilton, Lisa, Giles, Wayne R., and Smith, Godfrey L. (2007) Evidence of intercellular coupling between co-cultured adult rabbit ventricular myocytes and myofibroblasts. Journal of Physiology, 583 (1). pp. 225-236.

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Abstract

Intercellular coupling between ventricular myocytes and myofibroblasts was studied by co-culturing adult rabbit ventricular myocytes with previously prepared layers of cardiac myofibroblasts. Intercellular coupling was examined by: (i) tracking the movement of the fluorescent dye calcein; (ii) immunostaining for connexin 43 (Cx43); and (iii) measurement of intracellular [Ca2+] ([Ca2+]i). The effects of stimulating ventricular myocytes on the underlying myofibroblasts was examined by confocal measurements of [Ca2+]i using fluo-3. When ventricular myocytes were preloaded with calcein and co-cultured with myofibroblasts for 24 h, calcein fluorescence was detected in 52±4% (n=8 co-cultures) of surrounding myofibroblasts. Treatment with the gap junction uncoupler heptanol significantly reduced the movement of calcein (12±3%, n=6 co-cultures). Immunostaining showed expression of Cx43 in co-cultured myofibroblasts and myocytes. Field stimulation of ventricular myocytes co-culturedwithmyofibroblasts increasedmyofibroblast [Ca2+]i, no response was observed after treatment with heptanol or stimulation of fibroblasts in the absence of ventricular myocytes. Action potential parameters of ventricularmyocytes in co-culture were similar to control values. However, application of the hormone sphingosine-1-phosphate (S-1-P) to the co-culture caused a depolarization of ventricular myocytes to approximately −20 mV. Sphingosine-1-phosphate had no effect on ventricular myocytes alone. Voltage-clamp measurements of isolated myofibroblasts indicated that S-1-P activated a significant quasi-linear current with a reversal potential of approximately −40 mV. In conclusion, this study shows that stimulation of the ventricular myocyte influences the intracellular Ca2+ of the linked myofibroblast via connexons. These intercellular links also allow the myofibroblasts to influence the electrical activity of the myocyte. This work indicates the nature of the gap junction-mediated bi-directional interactions that occur between ventricular myocyte and myofibroblast.

Item ID: 9653
Item Type: Article (Refereed Research - C1)
ISSN: 1469-7793
Date Deposited: 04 May 2010 03:29
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1102 Cardiovascular Medicine and Haematology > 110201 Cardiology (incl Cardiovascular Diseases) @ 100%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920103 Cardiovascular System and Diseases @ 100%
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