Interstitial cells of Cajal and electrical activity of smooth muscle in porcine ileum
To identify the interstitial cells of Cajal in the porcine ileum for the first time immunohistochemically and to examine the electrical properties of intestinal smooth muscle in the same region. Methods:
In vitro intracellular microelectrode recordings were made from smooth muscle cells in cross-sectional preparations from abattoir-derived healthy porcine ileum. Immunohistochemical labelling of interstitial cells of Cajal was performed using an anti-Kit antibody. Results:
Slow waves were recorded in the circular muscle layer of all ileal preparations. The mean resting membrane potential of smooth muscle cells was −61.0 ± 1.3 mV. Slow waves had a mean amplitude of 8.5 ± 0.5 mV, a frequency of 9.9 ± 0.1 cycles per minute and a duration of 5.6 ± 0.1 s. A waxing and waning pattern of slow wave activity was occasionally observed. In addition, higher frequency spiking activity associated with contractions was observed in some recordings. The L-type calcium channel blocker nifedipine abolished both the spiking activity and the contractions, but had no significant effect on slow wave characteristics. Current-injection manipulation of the resting membrane potential had no effect on slow wave amplitude, frequency or duration. Kit-immunoreactive interstitial cells of Cajal were identified in the ileal samples and were present in the region of the myenteric plexus and in the circular and longitudinal muscle layers. Conclusion:
This study recorded slow waves in vitro and demonstrated immunohistochemically the presence of interstitial cells of Cajal in the normal porcine ileum. This study forms a basis for future physiological and pathophysiological comparative studies of intestinal motility.