Calcium and protein kinase C play an important role in Campylobacter jejuni-induced changes in Na+ and Cl− transport in rat ileum in vitro

Abstract

The pathophysiological mechanism of Campylobacter jejuni (enterotoxigenic) induced secretory diarrhoea remains least understood. To investigate the mechanism(s) involved, the unidirectional fluxes of Na+ and Cl- were measured across the C. jejuni live culture infected and control (non infected) rat ileum (unstriped), in vitro by Ussing technique under short circuit conditions, in the presence or absence of: Ca2+ ionophore A23187 (5 microM), 1-verapamil (100 microM), calmodulin (CaM) antagonist W-7 (100 microM), dantrolene (25 microM), protein kinase C (PKC) activator PMA (100 ng/ml) and H-7 (60 microM), selective inhibitor of PKC. There was net absorption of Na+ and enhanced Cl- secretion in infected animals while in control animals there was net absorption of Na+ and marginal secretion Cl-.Ca2+ ionophore A23187 mimicked the effects of C. jejuni infection whereas 1-verapamil had significant antisecretory effect on Na+ and Cl- secretion in infected animals. In vitro measurement of undirectional 45Ca fluxes in Ussing chamber experiments revealed net absorption of Ca2+ in infected rat ileum as compared to net secretion of Ca2+ in control rat ileum. These observations clearly indicate that there is increased stimulation of Ca2+ uptake from extracellular milieu to the enterocytes during C. jejuni-induced diarrhoea. The intracellular calcium levels (Ca2+]i (as measured by fluorescent probe Fura-2AM) were found to be raised significantly (P < 0.0001) in enterocytes isolated from C. jejuni infected ileum as compared to the enterocytes from control ileum. The observed increase in [Ca2+]i in enterocytes isolated from C. jejuni live culture supernatant treated rat ileum further shows the involvement of enterotoxin in diarrhoeal process. Dantrolene decreased significantly C. jejuni-induced net Na+ and Cl- secretion but it could not reverse it to absorption suggesting the partial involvement of Ca2+ mobilised from intracellular stores in mediating secretion. W-7 failed to inhibit the C. jejuni-induced net Na+ and Cl- secretion. In addition the CaM activity estimated in intestinal microvillar core remained same in both the control and C. jejuni infected animals. This indicates that C. jejuni-induced diarrhoea is not mediated through the activation of Ca(2+)-CaM complex pathway of the Ca2+ messenger system. The PKC activator PMA, induced net secretion of Na+ and Cl- in the control animals but it could not enhance further the C. jejuni-induced Na+ and Cl- secretion, suggesting that there is overlapping effect of PMA and C. jejuni live culture infection.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of lipopolysaccharide on D-fructose transport across rabbit jejunum

“…Calcium plays an important role in electrolyte intestinal transport regulation via Ca 2+ -calmodulin (CaM) and/or protein kinase C (PKC) systems [35]. Consequently, calcium and PKC are important in Campylobacter jejuni-induced changes in Na + and Cltransport in rat ileum in vitro [36]. CaM and PKC also control K + -transport in rat distal colon [37].…”

“…PKC is important in the sensitization of endothelial cells to bacterial endotoxin challenge [36]. PKC has also been related to the transport of electrolytes in rat colon and ileum [35,37] and sodium-glucose, L-arginine and L-alanine transport in different cell lines [39 -42].…”

Inhibitory effect of TNF‐α on the intestinal absorption of galactose

“…PKC plays an important cell signal transduction role in many physiological processes such as membrane functions [Nishizuka, 1992] or sensitizing endothelial cells to bacterial endotoxin challenge [Kanwar et al, 1995]. PKC has also been shown to contribute to electrolyte transport regulation in the rat colon and ileum [Kaur et al, 1993;Heinke et al, 1999], and to Dglucose, L-arginine, and L-alanine transport in several cell lines [Delezay et al, 1995;Pan and Stevens, 1995a,b;Vayro and Silverman, 1999].…”

Biodegradable Eri silk nanoparticles as a delivery vehicle for bovine lactoferrin against MDA-MB-231 and MCF-7 breast cancer cells

“…33,34 Western blot analysis illustrated that Fe-bLf loaded on silk NPs was present in the intact form after it was absorbed from the intestinal loops. This result showed the binding affinities of silk and bLf protein, as well as the ability of the Eri silk NPs to carry and successfully deliver the loaded bLf protein by maintaining …”