Basolateral PAR‐2 receptors mediate KCl secretion and inhibition of Na⁺ absorption in the mouse distal colon

Abstract

Proteinase‐activated receptor‐2 (PAR‐2) may participate in epithelial ion transport regulation. Here we examined the effect of mouse activating peptide (mAP), a specific activator of PAR‐2, on electrogenic transport of mouse distal colon using short‐circuit current (ISC) measurements. Under steady‐state conditions, apical application of amiloride (100 μm) revealed a positive ISC component of 74.3 ± 6.8 μA cm−2 indicating the presence of Na+ absorption, while apical Ba2+ (10 mm) identified a negative ISC component of 26.2 ± 1.8 μA cm−2 consistent with K+ secretion. Baseline Cl− secretion was minimal. Basolateral addition of 20 μm mAP produced a biphasic ISC response with an initial transient peak increase of 11.2 ± 0.9 μA cm−2, followed by a sustained fall to a level 31.2 ± 2.6 μA cm−2 (n= 43) below resting ISC. The peak response was due to Cl− secretion as it was preserved in the presence of amiloride but was largely reduced in the presence of basolateral bumetanide (20 μm) or in the absence of extracellular Cl−. The secondary decline of ISC was also attenuated by bumetanide and by Ba2+, indicating that it is partly due to a stimulation of K+ secretion. In addition, the amiloride‐sensitive ISC was slightly reduced by mAP, suggesting that inhibition of Na+ absorption also contributes to the ISC decline. Expression of PAR‐2 in mouse distal colon was confirmed using RT‐PCR and immunocytochemistry. We conclude that functional basolateral PAR‐2 is present in mouse distal colon and that its activation stimulates Cl− and K+ secretion while inhibiting baseline Na+ absorption.

Role for protease activity in visceral pain in irritable bowel syndrome

“…These results are in accordance with the concept that PAR 2 represents an important receptor mediating the symptoms of IBS (20). Thus, PAR 2 activation modifies intestinal chloride secretion, consistent with a role for this receptor in IBS-associated secretory dysfunctions (21)(22)(23)(24). PAR 2 agonists evoke an increase in intestinal barrier permeability (25,26), which is known to be associated with IBS symptoms in some patients (27,28) as well as in animal models (29).…”

PAR-2 agonists induce contraction of murine small intestine through neurokinin receptors

“…The prominent expression of PAR-2 along the entire GI length and the localization of PAR-2 in enterocytes, neuronal elements, and myocytes demonstrate the potential importance of PAR-2 in the regulation of GI function (18). PAR-2 agonists induce changes in intestinal epithelial cell transport in a number of species (9,21). PAR-2 also participates in the regulation of GI motility; however, the results are inconsistent.…”

Additional Disruption of the ClC-2 Cl- Channel Does Not Exacerbate the Cystic Fibrosis Phenotype of Cystic Fibrosis Transmembrane Conductance Regulator Mouse Models

“…The equivalent short circuit current (IЈ sc ) was calculated from V te and R te according to Ohm's law. Another set of experiments was performed essentially as described previously (27). Briefly, a tissue area of 0.28 cm 2 was mounted in a conventional Ussing chamber filled with bicarbonatebuffered Ringer's solution and gassed with 5% CO 2 .…”