Opioidergic regulation of contractile activity of lymphatic vessels

Abstract

The aim is to study the effect of endogenous opioid peptides on the contractile activity of lymphatic vessels in the white rat. Materials and methods . Under isometric conditions, the dynamics of spontaneous contractile activity of isolated annular segments of rat lymphatic vessels under the action of endogenous opioid peptides (beta-endorphin and endomorphin-1) was record; possible mechanisms of opiates action were studied. Results . The range of β-endorphin level 1×10 –11 –1×10 –8 M resulted in a decrease of the minute productivity of the lymphatic vessels, by 22%, mainly due to a decreasing of single contractions frequency. In the presence of blockers of voltage-gated and ATP-sensitive potassium channels and blockers of eNOS, the inhibitory effect was not manifest. Endomorphin-1, used in the concentration range of 1×10 –10 –1×10 –8 M, stimulated the contractile activity of the lymphatic vessels by an average of 15 %. The stimulatory effect was not manifest when using endomorphin-1 in the presence of a selective NK1 receptor antagonist. Conclusions . The inhibitory effect of β-endorphin is associated with the activation of voltage-dependent and ATP-sensitive potassium channels, endothelium-(NO)-dependent mechanisms. The action of endomorphin-1, stimulating lymphangionic motility, can be carry out through interaction with NK receptors.