Omega-3 fatty acids modulate ATPases involved in duodenal Ca absorption.
Dietary supplementation with fish oil that contains omega-3 polyunsaturated fatty acids has been shown to enhance bone density as well as duodenal calcium uptake in rats. The latter process is supported by membrane ATPases. The present in vitro study was undertaken to test the effect of omega-3 fatty acids on ATPase activity in isolated basolateral membranes from rat duodenal enterocytes. Ca-ATPase in calmodulin-stripped membranes was activated in a biphasic manner by docosahexanoic acid (DHA) (10-30 microg/ml) but not by eicosapentanoic acid (EPA). This effect was blocked partially by 0.5 microM calphostin (a protein kinase C blocker). DHA inhibited Na,K-ATPase (-49% of basal activity, [DHA]=30 microg/ml, P <0.01). This effect could be reversed partially by 50 microM genistein, a tyrosine kinase blocker. EPA also inhibited Na,K-ATPase: (-47% of basal activity, [EPA]=30 microg/ml, P <0.01), this effect was partially reversed by 100 microM indomethacin, a cyclo-oxygenase blocker. Omega-3 fatty acids are thus involved in multiple signalling effects that effect ATPases in BLM.
Haag
Marianne
M
Department of Physiology, University of Pretoria, PO Box 2034, Pretoria 0001, South Africa. mhaag@medic.up.ac.za
Magada
Olga N
ON
Claassen
Nico
N
Böhmer
Linde H
LH
Kruger
Marlena C
MC
D000042:Absorption / Q000187:drug effects; D000818:Animals; D001081:Apyrase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004386:Duodenum / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D020895:Enterocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology*; D008297:Male; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats
D004791:Enzyme Inhibitors; D015525:Fatty Acids, Omega-3; D009281:Naphthalenes; C061465:calphostin complex; D011493:Protein Kinase C; D001081:Apyrase; D002118:Calcium