Rectal Potential Difference and the Functional Expression of CFTR in the Gastrointestinal Epithelia in Cystic Fibrosis Mouse Models

Abstract

Cystic fibrosis (CF) is an autosomal recessive disease that results from mutations in the CF transmembrane conductance regulator (CFTR) gene. The effect of interventions aimed at correcting the CF electrophysiologic phenotype has been primarily measured using in vitro methods in gastrointestinal and respiratory epithelia. A reliable in vivo assay of CFTR function would be of great value in the investigation of pharmacologic interventions for CF mouse models. We performed the in vivo rectal potential difference (RPD) assay on three different mouse models. We then compared the in vivo data with the results obtained using the in vitro Ussing chamber method. The results from the in vitro method correlated closely with the results acquired using the in vivo method and were reproducible. The data suggest that the in vivo RPD assay is a reliable assay of functional CFTR expression in CF mouse models. (Pediatr Res 63: 73-78, 2008)

Colonic potassium handling

“…In the context of CFTR-mediated Cl − secretion and BK-mediated K + secretion, a recent study is worth mentioning. In this study, the resting transepithelial voltage was approximately −10 mV (lumen negative) in control mice [132]. In contrast, CFTR knockout tissue displayed a dramatically lower lumen-negative V te of close to 0 mV.…”

Myosin Ia is Required for CFTR Brush Border Membrane Trafficking and Ion Transport in the Mouse Small Intestine

“…During all experiments solutions were continuously gassed with 95%O 2 /5%CO 2 and warmed to 37 • C. Data were recorded continuously using the Acquire and Analyze software program (Physiologic Instruments). Initially segments were perfused with Krebs Bicarbonate Ringer's solution (KBR) and subsequently changed to a chloride-free Ringer's solution containing 5 mM barium hydroxide as previously described (54,55). Amiloride and forskolin were added to the chloride-free Ringer's solution at final concentrations of 10 −4 M and 10 −5 M, respectively.…”

On the measurement of the functional properties of the CFTR

“…Thus, measurements of changes of transepithelial potential V T in response to channels activators or blockers, or changing the permeant ions concentration, could reveal the contribution of different channels to the transepithelial potential. This technique is particularly suitable for studies on whole animals and can also be applied to human patients [46][47][48][49][50]. Transepithelial nasal or rectal potential can be measured introducing an electrode in the liquid layer adjacent to the apical side of the epithelia (the nose or the rectal cavities), and measuring the potential difference against a hypodermic reference electrode.…”