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Updated: Aug 26, 2026

Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy and Imaging
Published on: December 30, 2016
PKA regulation of bicarbonate and lactate movements across rat jejunal plasma membranes
Maria Novella Orsenigo1, Marisa Tosco, Umberto Laforenza
1Dipartimento di Scienze Biomolecolari e Biotechnologie, Universitá di Milano, Italy. novella.orsenigo@unimi.it
Background/Aims:
Evidence was previously given that the mechanisms involved in bicarbonate and lactate movements across rat jejunal enterocyte are modulated by PKC and Ca2+/CaM. Aim of this study was to investigate the possible role of PKA on bicarbonate and lactate transports.
Methods:
Enzymatic assays in isolated plasma membranes were performed. Moreover membrane vesicles, transiently opened and resealed, were treated with a phosphorylating solution (leading to PKA activation) and were used after that to perform uptake studies.
Results:
Enzymatic assays give evidence for the presence of PKA in plasma membranes from rat jejunum. Uptake experiments suggest that PKA stimulates the two systems that accomplish basolateral HCO3- efflux from the enterocyte, namely Cl-/ HCO3- exchanger and HCO3- conductance, without affecting HCO3- influx from the lumen mediated by Na+/H+ exchanger activity. Moreover basolateral H+-lactate symporter is stimulated by PKA, as well as the brush border isoform of Na+-glucose cotransporter SGLT1.
Conclusion:
PKA activation evokes individual responses that could be coordinated through cellular metabolism.
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