Colonic potassium and chloride secretion: role of cAMP and calcium

McCabe, R. D.; Smith, Philip L.

doi:10.1152/ajpgi.1985.248.1.g103

Cited by 32 publications

(28 citation statements)

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“…As demonstrated with rabbit and rat distal colon (Halm & Frizzell, 1991), the presence of amiloride in the mucosal solution did not alter K+ fluxes across guinea-pig distal colon (data not shown). The cyclo-oxygenase inhibitor indomethacin reduced spontaneous ion secretory activity in rabbit distal colon, presumably by inhibition of prostaglandin production (McCabe & Smith, 1985; (Fig. 1A), as also shown previously (Ishida & Suzuki, 1987 (Frizzell, Halm & Krasny, 1984; (Homaidan, Zhao & Burakoff, 1995 Halm & Frizzell, 1991) and PGE2 stimulates increased cell Ca2+ in human colonic crypts (Thum & Rechkemmer, 1994).…”

Section: Resultssupporting

confidence: 83%

Active potassium transport across guinea‐pig distal colon: action of secretagogues.

Rechkemmer¹,

Frizzell²,

Halm³

1996

The Journal of Physiology

123

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1. Adrenaline (5 uM) stimulated a K+ secretory current by 2-2 ftequiv h-' cm2 in isolated guinea-pig distal colonic epithelium. This secretory activity was inhibited entirely by addition of the loop diuretic bumetanide to the serosal solution. On-going K+ uptake via the absorptive pathway was unaltered by these changes.2. Prostaglandin E2 (PGE2, 2 /M) stimulated electrogenic K+ secretion and Cl-secretion by 3 0 and 3-6 ,tequiv h-cmM2, respectively. Serosal addition of bumetanide completely inhibited this K+ secretion but blocked only -70% of Cl-secretion. The bumetanideinsensitive Cl-secretory current was dependent on the presence of Cl-and HC03-in the bathing solutions. 3. Stimulation of electrogenic K+ secretion by PGE2 occurred with a half-maximal concentration of 4 nm, an affinity -300 times higher than that for stimulation of Clsecretion by PGE2.4. Forskolin (10 AM) stimulated Cl-secretion by 4-9 tequiv h-' cm2. The apparent K+ secretory rate was increased by only 1-5 ytequiv h-1 cm2. A bumetanide-insensitive shortcircuit current (Isc) was apparent and of the same size as that stimulated by PGE2.5. Addition of the Ca2+ ionophore A23187 (10 fSM), in the presence of indomethacin (1 /SM) to reduce prostaglandin production, inhibited the K+ absorptive pathway by 40% and concurrently stimulated a small rate of electrogenic K+ secretion. 6. Active K+ absorption was inhibited by the addition of ouabain, omeprazole or SCH28080 to the mucosal solution. Both omeprazole and SCH28080 also stimulated a small negative Isc, consistent with electrogenic K+ secretion. 7. Association of K+ absorption, K+ secretion and Cl-secretion is indicated by similarities in transport mechanism and by secretagogue regulation. In particular, maximal rates of K+ secretory current require uptake via apical membrane K+ pumps. Such interrelations support a common cellular locus for these ion transport pathways.Potassium transport across the epithelium lining mammalian distal colon occurs via both active secretory and active absorptive pathways (Halm & Frizzell, 1991). Regulation of these two oppositely directed transport processes permits a range of net flows. Active flow of K+ through the secretory pathway proceeds via a cellular mechanism similar to that for Cl-secretion ; uptake of K+ occurs through Na+-K+ pumps and Na+-K+-2Cl-cotransporters in the basolateral membrane with K+ exit from the cell through channels in the apical and basolateral membranes. The ratio of these K+ conductances together with K+ electrochemical gradients determine the rate of K+ secretion. A cellular mechanism for active K+ absorption has not been resolved as clearly.

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Section: Resultssupporting

confidence: 83%

Active potassium transport across guinea‐pig distal colon: action of secretagogues.

Rechkemmer¹,

Frizzell²,

Halm³

1996

The Journal of Physiology

123

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“…1) are also likely, at least in part, a consequence of the activation of K + secretion. In rabbit colon, A23187, 8-bromocyclic AMP, and PGE, (or PGE2) have been shown to stimulate both K + and Cl -secretions (MCCABE and SMITH, 1985). It is interesting that at higher concentrations of 8-bromocyclic AMP the decrease in Is~ was smaller when compared with low concentrations (Fig.…”

Section: Discussionmentioning

confidence: 89%

Synergism between calcium-mediated and cyclic AMP-mediated activation of chloride secretion in isolated guinea pig distal colon.

Yajima

Suzuki

1988

Jpn.J.Physiol

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Synergistic effects of Cat +-mediated secretagogues and cyclic AMP-mediated secretagogues on Cl -secretion by guinea pig distal colon were studied in vitro using Ussing chambers. Short-circuit current (ISO) and bidirectional fluxes of Z2Na + and 3601-were measured. Bethanechol (10-4 M, a Cat+-mediated secretagogue) caused an increase in ISO, which was enhanced 4-20 fold when the tissue was pretreated with prostaglandin E2 (10-'-10-6 M), vasoactive intestinal polypeptide (5 x 10-9-10_8 M) (cyclic AMP-mediated secretagogues), or 8-bromocyclic AMP (5 x 10-4-2 x 10 -3M). Measurement of 3601 flux showed that the increase in ISO in the presence of both 8-bromocyclic AMP and bethanechol resulted principally from increased Cl-secretion. On the other hand, the net absorptive flux of 22Na was not influenced under these conditions. Potentiation of the increase in ISO was also elicited by the combination of A23187 (5 x 10_6 M) and 8-bromocyclic AMP (10-3 M). The results are consistent with the notion that simultaneous activation of the cyclic AMP-mediated and Cat+-mediated systems produces a synergistic increase in colonic Clsecretion.

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“…carbachol) and cAMP (e.g. adenosine, VIP, cholera toxin, prostaglandin E 2 ) regulate the activities of these transporters and channels and thus regulate ion secretion (57)(58)(59)(60). Apical or basolateral adenosine, like VIP or cholera toxin, has been demonstrated to activate cAMP-dependent electrogenic chloride secretion through the activation of apical chloride channels (3,6).…”

Section: Fig 8 Ifn-␥ Inhibits the Expression Of Ac Isoforms 5 Andmentioning

confidence: 99%

Interferon-γ Down-regulates Adenosine 2b Receptor-mediated Signaling and Short Circuit Current in the Intestinal Epithelia by Inhibiting the Expression of Adenylate Cyclase

Kolachala

Asamoah

Wang

et al. 2005

Journal of Biological Chemistry

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Colonic potassium and chloride secretion: role of cAMP and calcium

Cited by 32 publications

References 0 publications

Active potassium transport across guinea‐pig distal colon: action of secretagogues.

Active potassium transport across guinea‐pig distal colon: action of secretagogues.

Synergism between calcium-mediated and cyclic AMP-mediated activation of chloride secretion in isolated guinea pig distal colon.

Interferon-γ Down-regulates Adenosine 2b Receptor-mediated Signaling and Short Circuit Current in the Intestinal Epithelia by Inhibiting the Expression of Adenylate Cyclase

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