Adenosine system and cell calcium translocation: interference of calcium channel blockers.
Adenosine is able to inhibit in vitro neutrophil functions induced by formyl-methionyl-leucyl-phenylalanine (FMLP) and A23187, but not phorbol 12-myristate 13-acetate (PMA). The inhibiting activity on A23187 is reversed by increasing extracellular Ca2++ concentration. The calcium entry blocker flunarizine shows an activity very similar to that of adenosine. Both adenosine and flunarizine prevent Ca++ influx into activated neutrophils as detected by the fluorescent Ca++ chelator Quin-2. Finally, flunarizine binds to the neutrophil membrane and adenosine competitively inhibits flunarizine binding as assessed by 1H-Nuclear Magnetic Resonance (1H-NMR) technique, thus indicating that the two agents share a common binding site on the cell membrane.
Laghi Pasini
F
F
Istituto di Patologia Medica, University of Siena, Italy.
Capecchi
P L
PL
Pasqui
A L
AL
Ceccatelli
L
L
Mazza
S
S
Gistri
A
A
Di Perri
T
T
D000241:Adenosine / Q000494:pharmacology*; D001692:Biological Transport; D002118:Calcium / Q000493:pharmacokinetics*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002462:Cell Membrane; D005444:Flunarizine / Q000494:pharmacology*; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D009504:Neutrophils / Q000187:drug effects* / Q000502:physiology
D002121:Calcium Channel Blockers; D000241:Adenosine; D005444:Flunarizine; D002118:Calcium