Calcium-tolerant single cell preparations from the atrioventricular node (AVN) have contributed to the understanding of the electrophysiology of this region of the heart (e.g. Hancox et al. 1993; Habuchi et al. 1995; Martynyuk et al. 1995; Munk et al. 1996). The morphology of the AVN in rabbit heart has been well characterised (Anderson et al. 1974) and, to date, single AVN cell preparations have derived from this species. In the present study, we aimed to determine the feasibility of isolating from the guinea-pig AVN single cells suitable for electrophysiological recording.

Adult male guinea-pigs were killed humanely by cervical dislocation. Their hearts were then rapidly removed and were perfused retrogradely with a solution containing collagenase and protease. The entire AVN region was excised and cells released by a combination of mechanical and enzymatic dispersion (Hancox et al. 1993). Cells were stored in a high-K⁺, low-Ca²⁺ solution until use. Rod and spindle-shaped cells were obtained; these showed a mean (± S.E.M.) length of 108.8 ± 2.5 µm and mean width of 11.8 ± 1.5 µm (n = 65 cells). The mean cell capacitance measured from thirteen cells was 27.1 ± 0.4 pF.This work was funded by The Wellcome Trust.

Figure 1.

Some cells exhibited regular, spontaneous contractions in a Ca²⁺-containing Tyrode solution. Whole-cell current-clamp recordings from beating cells at 37 °C, using a K⁺-based internal dialysate, showed spontaneous action potentials (e.g. Fig. 1).

Although further work is required to optimise the isolation method for these cells, our initial findings indicate that it is possible to isolate calcium-tolerant cells from the guinea-pig AVN and that these cells can exhibit spontaneous activity. The availability of an alternative single AVN cell preparation to that from rabbit may be of value in understanding the cellular electrophysiology of the AVN.Anderson, R.H., Janse, M.J., van Capelle, F.J.L., Bilette, J., Becker, A.E. & Durrer, D. (1974). Circ. Res. 35, 909-922.

Habuchi, Y., Han, X.Q. & Giles, W.R. (1995). Heart Vessels S9, 203-206.

Hancox, J.C., Levi, A.J., Lee, C.O. & Heap, P. (1993). Am. J. Physiol. 265, H755-766.

Martynyuk, A.E., Kane, K.A., Cobbe, S.M. & Rankin, A.C. (1995). Cardiovasc. Res. 30, 668-675.

Munk, A.A., Adjemian, R.A., Zhao, J., Ogbaghebriel, A. & Shrier, A. (1996). J. Physiol. 493, 801-818. abstract