Functional Investigations: Stretch-Effects on Single Cardiac Myocyte Function

Dr Christian Bollensdorff and Ms Ken Wang

Many of the systemic effects of cardiac mechano-electric coupling can be studied by subjecting isolated cardiac myocytes to defined mechanical interventions, such as using carbon fibres to control the force-length behaviour of individual cells. The carbon fibre technique can be combined with direct electrical measurements (e.g. using patch pipettes) and with optical approaches based on ion or membrane voltage-sensitive dye recordings. These can be used, for example, to explore stretch effects on calcium sparks – believed to represent ‘unitary release events’ of calcium from intra-cellular stores called sarcoplasmic reticulum.

Present investigations focus at identifying the mechanisms of action of Apelin, the most potent positive ‘inotropic’ (i.e. force-enhancing) peptide known to date (it is effective at nanomolar concentrations, i.e. at a billionth of the chemical standard unit ‘Mol’ per litre).

Funding: BHF.

Recent papers:

• Iribe G, Ward CW, Camelliti P, Bollensdorff C, Mason F, Burton RAB, Garny A, Morphew M, Hoenger A, Lederer WJ & Kohl P. Axial stretch of rat single ventricular cardiomyocytes causes an acute and transient increase in Ca²⁺ spark rate. Circulation Research 2009/104:787-795 (DOI; cover; editorial).
• Iribe G & Kohl P. Axial stretch enhances sarcoplasmic reticulum Ca²⁺ leak and cellular Ca²⁺ reuptake in Guinea pig ventricular myocytes: experiments and models. Progress in Biophysics and Molecular Biology 2008/97: 298–311. (DOI)
• Iribe G, Helmes M & Kohl P. Force-length relations in isolated intact cardiomyocytes subjected to dynamic changes in mechanical load. American Journal of Physiology 2007/292: H1487-H1497 (AJP).