Pilocarpine-induced relaxation of rat tail artery by a non-cholinergic mechanism and in the absence of an intact endothelium

Profiling the endothelial function using both peripheral artery tonometry (EndoPAT) and Laser Doppler Flowmetry (LD) - Complementary studies or waste of time?

Endothelial dysfunction (ED) plays a key role in developing of cardiovascular diseases and is an important predictor of future cardiovascular events. Nevertheless, there is no established method assessing endothelial function in general population. The most popular protocol includes the ultrasound-flow-mediated-dilation, but its repeatability is operator-dependent. We intended to compare the two other operator-independent methods assessing endothelial function - the EndoPAT and Laser Doppler flowmetry (LD), and we endeavored to place them on current individual profile of biochemical cardiovascular risk and endothelial function. A total of 61 clinically healthy subjects (aged 29 ± 1y) were investigated. The blood was collected for conventional cardiovascular risk markers, the NO-pathway metabolites (ADMA, L-arginine, SDMA), oxidative-stress-markers (MDA, thiol-index) as well as endothelial and platelet activation markers (sICAM1, sVCAM1, PAI-1, sE-selectin, sP-selectin, VEGF). Subsequently, all participants underwent examination by both EndoPAT and LD. There was a poor correlation between EndoPAT and LD results. No significant differences between participants with preserved and impaired endothelial function regarding endothelial activation nor cardiovascular risk markers were observed. Both methods assess endothelial function independently from the profile of endothelial pro/anti-inflammatory status and conventional risk factors, therefore further prospective studies are needed in order to verify their additional value in the cardiovascular risk stratification.

Variation in mRNA expression of alpha-adrenergic, neurokinin and muscarinic receptors amongst four arteries of the rat

Different mechanisms mediate constriction and dilation in different vascular beds. We have used reverse transcription-polymerase chain reaction to investigate whether specific patterns of receptor gene expression may underlie these variable responses. Total RNA, from the basilar, pulmonary, mesenteric and tail arteries of anaesthetised adult Wistar rats, was reverse transcribed and amplified using primers specific for the molecular subtypes of the alpha 1(A, B, D)- and alpha 2(A, B, C)-adrenergic, neurokinin (NK1-NK3) and muscarinic (m1-m5), receptors. Results showed that the pattern of gene expression was variable with no two arteries having the same receptor profile. Messenger RNA for the alpha 1A, alpha 1B, alpha 2B, NK1, NK3, m3 and m5 receptor subtypes were detected in all vessels studied while the remaining subtypes showed a variable expression amongst the arteries. This is the first description of mRNA for the m5 muscarinic receptor in peripheral tissue. The NK3 receptor was the major neurokinin receptor expressed in all vessels except the pulmonary artery, in which the NK1 receptor was also strongly expressed. We conclude that each artery expressed a specific receptor array which may permit some unique neural and hormonal controls.