The four PARs are expressed throughout the gastrointestinal tract in different cell types . For example, immunoreactive PARj and PAR2 have been detected in more than 60% of neurons from the myenteric plexus of the guinea pig small intestine, both in primary cultures and in whole mounts of myenteric tissues. A large proportion of neurons expressing substance P, a primary excitatory neuropeptide, also expressed PARj (89%) and PAR2 (50%). Similarly, a large percentage of neurons expressing VIP, which acts as an inhibitory motor transmitter, also expressed PARj (44%) and PAR2 (90%) . More than 50% of neurons expressing PARj also expressed PAR2.
PARj and PAR2 are also expressed by extrinsic enteric neurons. PAR2’like immunoreactivity and PAR2 mRNA expression have also been detected in rat isolated dorsal root ganglia neurons. Among the sensory neurons expressing PAR2, approximately 40% coexpressed CGRP and 30% coexpressed substance P. PARj is also located in dorsal root ganglia neurons, where it often coexpressed with substance P .
PARj and PAR2 are also functional in ENS cells. Linden and colleagues have shown that PAR2 agonists signal guinea pig myenteric neurons, inducing depolarization and increasing the number of action potentials in isolated cells. Reed and colleagues have shown that PAR2 agonists evoked depolarization and long term excitation in submucosal neurons isolated from the guinea pig ileum. Both PARj and PAR2 agonists stimulate calcium mobilization in isolated guinea pig myenteric neurons and dorsal root ganglia neurons. Find best deals online – viagra super active online buy here can be available every time you visit.
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