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

Chilton, L., Giles, W.R. and Smith, G.L. (2007) Evidence of intercellular coupling between co-cultured adult rabbit ventricular myocytes and myofibroblasts. Journal of Physiology, 583(1), pp. 225-236. (doi: 10.1113/jphysiol.2007.135038)

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-cultured with myofibroblasts increased myofibroblast [Ca²⁺](i), no response was observed after treatment with heptanol or stimulation of fibroblasts in the absence of ventricular myocytes. Action potential parameters of ventricular myocytes 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 Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Smith, Professor Godfrey
• Authors: Chilton, L., Giles, W.R., and Smith, G.L.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Journal of Physiology
• ISSN: 0022-3751
• ISSN (Online): 1469-7793
• Published Online: 14 June 2007