Roles of adenosine and theophylline on the recovery of adenine nucleotides in postischemic cultured renal tubular cells.
The effect of adenosine (ADO) on the recovery of cellular adenine nucleotides (AN) was evaluated in the cultured cells deprived of oxygen and substrates (ischemia) and in nonischemic cells (control). The primary cultured cells were obtained from microdissected rabbit proximal straight tubules. Ten-day-old cultured cells were made ischemic for 6 hr, and allowed to recover for 24 hr. At the end of ischemia, cells were incubated with ADO, theophylline (T), dipyridamole (D), coformycin (C) or combined agents for 3 hr. Total AN (TAN) were determined after 3 and 24 hr of recovery. The results, after 3 hr of incubation, suggest that in both control and ischemic cells, ADO is taken up by cultured cells and is preferentially converted to nucleotides. This effect is blocked by D, which inhibits ADO uptake, uninfluenced by C, which inhibits ADO deaminase and potentiated by T, which inhibits 5'-nucleotidase. After 24 hr of recovery, the beneficial effects of ADO alone or combined D, C, or T, on TAN were not seen in control cells. In contrast, in the ischemic cells, after 24 hr of recovery, ADO + T normalized ATP, ADP and TAN to the preischemic levels. T alone significantly increased ATP after 24 hr of recovery. To demonstrate further that the beneficial effect of T is due to inhibition of 5'-nucleotidase, cells were treated with adenosine alpha, beta-methylene diphosphate in the same manner as T. Combined ADO + adenosine alpha, beta-methylene diphosphate normalized ATP, ADP and TAN after 24 hr of recovery. This finding suggests that inhibition of 5'-nucleotidase improves postischemic AN.(ABSTRACT TRUNCATED AT 250 WORDS)
Cadnapaphornchai
P
P
Department of Medicine, Wayne State University, School of Medicine, Detroit, Michigan.
Kellner
D
D
Golembieski
A
A
McDonald
F D
FD
D000241:Adenosine / Q000494:pharmacology*; D000244:Adenosine Diphosphate / Q000302:isolation & purification / Q000378:metabolism*; D000249:Adenosine Monophosphate / Q000302:isolation & purification / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D007511:Ischemia / Q000378:metabolism*; D007684:Kidney Tubules / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism; D011817:Rabbits; D013806:Theophylline / Q000494:pharmacology*
D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D013806:Theophylline; D000241:Adenosine