Vardenafil protects isolated rat hearts at reperfusion dependent on GC and PKG.
OBJECTIVE
The type-5 PDE inhibitor vardenafil reduces myocardial infarct size in situ, following ischemia/reperfusion, when applied at reperfusion in animal models. Little is known about the underlying protective signaling. Here, we test whether vardenafil is protective in rat isolated hearts and in a cell model of calcium stress.


METHODS
Infarct size in rat isolated hearts was measured after a 30 min regional ischemia and 120 min reperfusion. Vardenafil (1 nM-1 microM) was infused during reperfusion. HL-1 cardiomyocytes were loaded with tetramethylrhodamine ethyl ester (TMRE), a fluorescent marker of mitochondrial membrane potential (psi m).


RESULTS
Vardenafil at reperfusion reduced infarct size as percentage of the ischemic zone from 45.8+/-2.0% in control hearts to 26.2+/-2.7% (P<0.001) only at 10 nM, whereas higher or lower dosages failed to protect. This protective effect was blocked by co-administration of either the GC inhibitor, 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), or the PKG inhibitor, KT-5823. HL-1 cardiomyocytes, loaded with TMRE, were treated for 80 min with the calcium ionophore, calcimycin, to induce calcium stress. This reduced the mean cell fluorescence to 63.3 +/- 3.8% of baseline values and vardenafil protected against this fall (78.6 +/- 3.6%, P<0.01). The vardenafil-induced protection of HL-1 cells was blocked by ODQ, KT-5823 or the PKG-inhibiting peptides DT-2 and DT-3, confirming a role for GC and PKG.


CONCLUSIONS
These results further support the hypothesis that PDE-5 inhibitors are protective in ischemic hearts, in addition to their known clinical effects in the treatment of erectile dysfunction in men.
Maas
O
O
Department of Cardiology, Ernst-Moritz-Arndt University, Greifswald, Germany.
Donat
U
U
Frenzel
M
M
Rütz
T
T
Kroemer
H K
HK
Felix
S B
SB
Krieg
T
T
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002227:Carbazoles / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000502:physiology; D016923:Cell Death; D002460:Cell Line; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000502:physiology*; D007093:Imidazoles / Q000627:therapeutic use*; D066298:In Vitro Techniques; D008840:Microfilament Proteins / Q000502:physiology; D008929:Mitochondria, Heart / Q000187:drug effects; D051336:Mitochondrial Membranes / Q000187:drug effects; D009203:Myocardial Infarction / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000473:pathology; D010069:Oxadiazoles / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000627:therapeutic use*; D010750:Phosphoproteins / Q000502:physiology; D010879:Piperazines / Q000627:therapeutic use*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D013450:Sulfones / Q000627:therapeutic use; D014227:Triazines / Q000627:therapeutic use; D000069058:Vardenafil Dihydrochloride; D000098662:Vasodilator-Stimulated Phosphoprotein
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D002227:Carbazoles; D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D007093:Imidazoles; D008840:Microfilament Proteins; D010069:Oxadiazoles; D010726:Phosphodiesterase Inhibitors; D010750:Phosphoproteins; D010879:Piperazines; D011810:Quinoxalines; D013450:Sulfones; D014227:Triazines; D000098662:Vasodilator-Stimulated Phosphoprotein; C073601:KT 5823; D000069058:Vardenafil Dihydrochloride; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D002118:Calcium