[NO-dependent. Modulation of contractile function in capsule of lymph nodes].

Phase and tonic contractions of capsular smooth muscles of bovine mesenteric lymph nodes were studied in vitro. Smooth muscle cells of the node capsule demonstrated spontaneous contractile activity; frequency of spontaneous phase contractions was averaged 1.1 +/- 0.14 min(-1), amplitude 1.7 +/- 0.21 mH. Sodium nitroprusside (0.1-1 microM) and acethylcholine (1 microM) reduced frequency and amplitude of phase contractions of smooth muscles of the lymph node, sodium nitroprusside (1 microM) arrested spontaneous contractile activity completely and decreased tone of the smooth muscle cells. Preliminary incubation of tissues with L-NAME, methylene blue or glibenclamide reduced the relaxation effect of acethylcholine considerably. We suggest that endothelial cells of subcapsular sinus of the lymph node produce NO which results in opening of ATP-sensitive K(+)-channels of smooth muscle cell membrane by means of cascade reaction and the relaxation of smooth muscle.