pH stat studies on bicarbonate secretion in the isolated mouse ileum

Abstract

Bicarbonate secretion occurs in almost all segments of the gastrointestinal tract. This study examined HCO 3 − secretion in the ileum, since it is less understood than HCO 3 − secretion in other intestinal segments. Mouse ileal mucosa was mounted in vitro in Ussing chambers, and the mucosal alkalinization rate (J OH ) was determined by pH stat titration, while the mucosal side was bathed with a buffer-free solution (100% O 2 ) and the serosal side with a HCO 3 − /CO 2 -buffered solution. The transmural potential difference (PD) was recorded. The mucosal alkalinization rate (J OH ) was higher in the presence of mucosal Cl − than in its absence. Forskolin, an activator of adenylate cyclase, enhanced J OH and PD in both the presence and absence of mucosal Cl − . Mucosal SO 4 2− also caused an increase in J OH , although the magnitude was smaller than that induced by Cl − . Mucosal Cl − -dependent J OH was partially inhibited by acetazolamide, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), tenidap and probably also by niflumic acid, but not by glibenclamide, DIDS or bumetanide. The forskolin-induced J OH value and PD were both inhibited by NPPB and probably also by tenidap. It is concluded that HCO 3 − secretion in the ileum follows a mucosal Cl −

Effects of acid-base variables and the role of carbonic anhydrase on oxalate secretion by the mouse intestine in vitro

“…B and B), and consistent with the abolition of DIDS‐sensitive (mucosal Cl − ‐dependent) secretion by the mouse distal ileum following the removal of serosal /CO 2 (Uchiyama et al. ; Zhang et al. ).…”

“…This notion was corroborated by the inability of CA inhibitor ethoxzolamide to impact Cl À fluxes (Figs. 3B and 5B), and consistent with the abolition of DIDS-sensitive (mucosal Cl À -dependent) HCO À 3 secretion by the mouse distal ileum following the removal of serosal HCO À 3 /CO 2 (Uchiyama et al 2007;Zhang et al 2007). A role for CA in the mouse ileum cannot be dismissed entirely as Uchiyama et al (2007) observed that Cl À -dependent HCO À 3 secretion was reduced~30% in the presence of 100 lmol/L acetazolamide.…”

“…3B and 5B), and consistent with the abolition of DIDS-sensitive (mucosal Cl À -dependent) HCO À 3 secretion by the mouse distal ileum following the removal of serosal HCO À 3 /CO 2 (Uchiyama et al 2007;Zhang et al 2007). A role for CA in the mouse ileum cannot be dismissed entirely as Uchiyama et al (2007) observed that Cl À -dependent HCO À 3 secretion was reduced~30% in the presence of 100 lmol/L acetazolamide. In contrast, net Cl À absorption by the rat ileum was sustained in the absence of HCO À 3 /CO 2 (Vaccarezza and Charney 1988), and furthermore was sensitive to methazolamide (Charney et al 2002a), indicating a prominent contribution of CA to ileal transport.…”

“…A role for CA in the mouse ileum cannot be dismissed entirely as Uchiyama et al. () observed that Cl − ‐dependent secretion was reduced ~ 30% in the presence of 100 μ mol/L acetazolamide. In contrast, net Cl − absorption by the rat ileum was sustained in the absence of /CO 2 (Vaccarezza and Charney ), and furthermore was sensitive to methazolamide (Charney et al.…”

Combinatorial effects of quercetin and sex-steroids on fluid and electrolytes’ (Na+, Cl-, HCO3-) secretory mechanisms in the uterus of ovariectomised female Sprague-Dawley rats

“…Quercetin could have exerted its’ effect through the GP-ACII-CAMP signaling pathways that is known to participate in ion channels/membrane transporters’ functions [ 27 , 28 ] ACII-GP-cAMP has been shown to be involved in CFTR and SLC26A6 activation which could lead to the increased in HCO 3 - secretion. [ 29 ]. cAMP is required for SLC26A6 and CFTR functions in the pancreas and salivary ductal epithelial cell [ 30 ].…”