Excitability of canine colon circular muscle disconnected from the network of interstitial cells of Cajal (original) (raw)

1992, Canadian Journal of Physiology and Pharmacology

of canine colon circu1ar muscle disconnected from the network of interstifa1 cells of Cajal. Can. J . Physiol. Pharmacol. 70: 289 -295. The 6 cpm omnipresent slow waves recorded in the circular muscle (CM) layer of canine colon are generated at the submucosal surhce of the CM layer. After removal of the submucosal network of interstitial cells of Cajal (ICC), 66% of the CM preparations (25 sf 38) were quiescent in Krebs solution. In the presence of cahachol, seven of nine sf these spntaneously quiescent CM preparations demonstrated slow wave-like activity with mean frequency, duration and amplitude of 5.9 + 0.4 cpm, 2.8 + 6.5 s, and 0.8 f 0.2 ~I V , respectively. Similar slow wave-like activities were induced by TEA (seven out of eight quiescent CM preparations) with frequency, duration and amplitude of 6.1 + 0.2 cprn, 2.7 + 0.5 s, and 1.0 + 0.2 mV, respectively, and by BaCB, (eight of eight quiescent CM preparations) with frequency, duration, and amplitude of 6.3 'r 0.3 cpm, I.$ f 0.2 s, and 0.5 + 0.1 mV, respectively. All the induced activities were abolished in the presence of H pM D6W. CM preparations with the submucosal ICC network intact (HCC -CM) showed slow wave activity in Krebs solution at a frequency of 6.2 t 0.2 cprn, a duration s f 3.6 f 0.2 s, and an amplitude of 1.0 + 0. I mV (n = 22). When ICC-CM preparations were stimulated by BaCl,, carbachol. or TEA, the slaw wave frequency did not change significantly, but the duration increased as well as the amplitude. In the presence of D600, the upstroke of slow waves remained and the frequency was not affected. The ability to generate slow wave-like activity after potassium conductance blockade in spontaneously quiescent CM disconnected from the ICC network suggested that circular muscle cells have ionic mechanisms for intrinsic oscillatory activity and are capable sf actively participating in the conduction and generation of slow waves. LILJ, L. W. C., DANIEL, E. E., et HL~IZINGA, 5. D. 1992. Excitability of canine colon circular nluscle disconnected from the network of interstital cells of Cajal. Can. J. Physiol. Pharmacol. 70 : 289-295. Les ondes Eentes ominipresentes de 6 cpm, enregistrtes dans la couche de muscle circulaire (MC) du colon du chien, sont produites i Ea surface sous-muqueuse de la couche de MC. Aprks l'extraction de cellules interstitielles de Cajal (CIC) du reseala sous-muqueux, 66% des preparations de MC (25 sur 38) ont Ct C inactives dans des solutions de Krebs. En presence de carbachol, sept SUH neuf de ces preparations de MC spontankment inactives ont dCmesntrC une activite de type onde lente, avec une frkquence, durte et amplitude moyennes de 5 ,0 f 0,4 cpm, 2,8 f 0,5 s et 0,8 i 0,2 mV, respectivernent. Des activitCs de type onde lente similaires ont tte iinduites par le TEA (sept sur huit des preparations inactives), avec une frtquence, durCe et amplitude de 6,1 f 0,2 cpm, 2,7 + 0,5 s et 1,0 f O,2 mV, respectivernent, et par le BaCl, (huit sur huit des pr6parations de MC inactives) avec une frequence, durte et amplitude de 6.3 + 0,3 cpm. 1,8 + 0,2 s et 0,5 f 0, I mV,