Protamine cardiotoxicity and nitric oxide.
OBJECTIVE
The purpose of this study is to assess the role of the nitric oxide (NO) pathway in protamine-induced cardiotoxicity and to formulate a possible explanation for this adverse effect.


METHODS
Isolated rat hearts were perfused by Krebs--Henseleit (KH) solution using a modified Langendorff model. They were randomized into three groups: A, 40 min perfusion with KH solution; B, 20 min perfusion with KH solution and 20 min with protamine; C, as B but Ng-monomethyl-L-arginine (L-NMMA), a non-selective inhibitor of the NO pathway, was added during 40 min of the perfusion period. Left ventricular (LV) function was measured every 10 min. NO and tumor necrosis factor-alpha (TNF) were detected in the effluent from the coronary sinus (CS) and in the supernatant of the cardiac myocytes culture. Nitric oxide synthases (NOS) mRNA levels were determined in groups A and B from LV samples at baseline and after 40 min of perfusion.


RESULTS
We found that protamine at a dose of 12 microg/ml causes significant depression of LV function (decreased peak systolic pressure to 22.5+/-3.2% and dP/dt max to 22.9+/-3.1%). L-NMMA did not prevent protamine cardiotoxicity. NOS mRNA was not detected from LV samples in any group. The NO in the effluent from the CS and from the supernatant of the cardiomyocytes culture was below detectable levels. However, a significant amount of TNF was measured in the effluent from the CS (108+/-17 pg/min for group B and 117+/-13 pg/min for group C) and in the supernatant of the cardiomyocytes culture (65+/-21 pg/ml).


CONCLUSIONS
This study suggests that direct protamine-induced cardiotoxicity does not depend on the NO pathway. Our finding that protamine induced TNF release by cardiomyocytes can shed new light on the understanding of protamine cardiotoxicity.
Pevni
D
D
Department of Cardiothoracic Surgery, Tel Aviv Sourasky Medical Center, 6 Weizmann Street, Tel Aviv 64239, Israel. shapiraiz@tasmc.health.gov.il
Frolkis
I
I
Iaina
A
A
Wollman
Y
Y
Chernichovski
T
T
Shapira
I
I
Uretzky
G
G
Mohr
R
R
D000818:Animals; D006321:Heart / Q000187:drug effects*; D006494:Heparin Antagonists / Q000633:toxicity*; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D010477:Perfusion; D011479:Protamines / Q000633:toxicity*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D016277:Ventricular Function, Left / Q000187:drug effects
D006494:Heparin Antagonists; D011479:Protamines; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat