Renal hypoxanthine balance in cardiac surgery: effects of felodipine.
OBJECTIVE
To test the hypothesis that felodipine, a renal vasodilator, can prevent a release of hypoxanthine during rewarming after moderate hypothermic cardiopulmonary bypass and that this is related to improved renal oxygen supply.


METHODS
A prospective, randomized, and controlled study.


METHODS
Operating room in the cardiothoracic surgery department of a university hospital.


METHODS
Twenty-two patients submitted to elective first-time coronary bypass surgery.


METHODS
A catheter was placed in the left renal vein for thermodilution renal blood flow (RBF) measurement and blood sampling. In 11 patients, felodipine was infused during the hypothermic period of cardiopulmonary bypass.


RESULTS
Renal uptake (renal arteriovenous concentration difference x RBF) of hypoxanthine was maintained during rewarming in felodipine-treated patients but not in control patients (55+/-28 v. -39+/-1 nmol/min, p<0.05). Oxygen consumption was higher after felodipine infusion despite unchanged total RBF. A positive correlation between renal oxygen consumption and hypoxanthine uptake and release (r = 0.74, p<0.01) was observed.


CONCLUSIONS
Felodipine maintained renal uptake of hypoxanthine during rewarming after hypothermic cardiopulmonary bypass. This maintenance is the effect of improved renal oxygen supply secondary to improved nutritive blood flow at the expense of nonnutritive renal blood flow.
Jeppsson
A
A
Department of Thoracic and Cardiovascular Surgery, Sahlgrenska University Hospital, Göteborg, Sweden.
Andersson
L G
LG
Ekroth
R
R
Joachimsson
P O
PO
D000368:Aged; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D017558:Elective Surgical Procedures; D015736:Felodipine / Q000627:therapeutic use*; D006801:Humans; D007036:Hypothermia, Induced; D019271:Hypoxanthine / Q000378:metabolism*; D007668:Kidney / Q000098:blood supply / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000187:drug effects; D011446:Prospective Studies; D013815:Thermodilution; D014665:Vasodilator Agents / Q000627:therapeutic use*
D002121:Calcium Channel Blockers; D014665:Vasodilator Agents; D019271:Hypoxanthine; D015736:Felodipine