Effect of Histamine on Contractile Activity of Smooth Muscles in Bovine Mesenteric Lymph Nodes

The effects of histamine and mechanisms of its action on the capsular smooth muscle cells of mesenteric lymph nodes were examined on isolated capsular strips under isometric conditions. Histamine (1 × 10-8-5 × 10-7 M) decreased the tone of capsular smooth muscle cells and the frequency of phasic contractions. At high concentrations (more than 5 × 10-6 M), histamine increased the amplitude and frequency of phasic contractions against the background of increased tonic stress. The effects of histamine were dose-dependent and were realized via direct stimulation of H1- and H2-receptors on the membrane of smooth muscle cells.