Evidence of Functional Ryanodine Receptors in Rat Mesenteric Collecting Lymphatic Vessels.

Evidence of Functional Ryanodine Receptors in Rat Mesenteric Collecting Lymphatic Vessels. Am J Physiol Heart Circ Physiol. 2019 Jul 05;: Authors: Jo M, Trujillo AN, Yang Y, Breslin JW Abstract In the current study, the potential contributions of ryanodine receptors (RyR) to intrinsic pumping and responsiveness to substance P (SP) were investigated in isolated rat mesenteric collecting lymphatic vessels. Responses to SP were characterized in lymphatic vessels in the absence or presence of pretreatment with nifedipine to block L-type Ca2+ channels, caffeine to block normal release and uptake of Ca2+ from the sarcoplasmic reticulum (SR), ryanodine to block all RyR isoforms, or dantrolene to more selectively block RyR1 and RyR3. RyR expression and localization in lymphatics was also assessed by qPCR and immunofluorescence confocal microscopy. The results show that SP normally elicits a significant increase in contraction frequency and a decrease in end-diastolic diameter. In the presence of nifedipine, phasic contractions stop, yet subsequent SP treatment still elicits a strong tonic contraction. Caffeine treatment gradually relaxes lymphatics causing a loss of phasic contractions, and prevents subsequent SP-induced tonic contraction. Ryanodine also gradually diminishes phasic contractions but without causing vessel relaxation, and significantly inhibits the SP-induced tonic contraction. Dantrolene treatment did not significantly impair...
Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Tags: Am J Physiol Heart Circ Physiol Source Type: research