title: Protein kinase C regulation of rat jejunal transport system: mechanisms involved in lactate movement.
abstract: We examined whether protein kinase C (PKC) modulates the transport systems involved in lactate movements across the plasma membranes of rat jejunum. In vitro phosphorylated membrane vesicles were used to perform uptake studies, the results of which suggested that PKC activation exerts an inhibitory effect on basolateral H+-lactate symport, as well as on apical N-+glucose cotransport. The specificity of the response to PKC was confirmed by using staurosporine, chelerythrine or 4-alpha-PMA. Experiments performed using the whole tissue incubated in vitro confirmed the reduction of lactate transport elicited by PKC and gave evidence for an associated inhibition of fluid transport. Na+K+-ATPase activity seems to be unaffected by the kinase and inhibited by Ca2+. Taken together, our results suggest that the overall action of PKC results from the simultaneous modulation of multiple pathways, targeted to a reduction of both lactate and bicarbonate transports without altering cell pH homeostasis.
authors.affiliation: Dipartimento di Fisiologia e Biochimica Generali, Universitá di Milano, Pavia, Italy. marisa.tosco@unimi.it
authors.forename: Marisa
authors.initials: M
authors.lastname: Tosco
authors.forename: Maria Novella
authors.initials: MN
authors.lastname: Orsenigo
authors.forename: Giulia
authors.initials: G
authors.lastname: Gastaldi
authors.forename: Alide
authors.initials: A
authors.lastname: Faelli
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D020895:Enterocytes / Q000201:enzymology; D004789:Enzyme Activation / Q000502:physiology; D066298:In Vitro Techniques; D007583:Jejunum / Q000166:cytology / Q000201:enzymology*; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D019344:Lactic Acid; D011493:Protein Kinase C