Our results showed that CNP, a secreted multifactorial molecule, was indeed effective in suppressing fibroproliferative response in injured arteries and suggest that the potent antiproliferation effect may not be the most critical factor for the effective suppression of neointimal formation. An adenovirus-mediated expression of CNP could be an effective and site-specific form of molecular intervention in proliferative arterial diseases.

Abstract-We previously observed that adenovirus-mediated expression of C-type natriuretic peptide (CNP) markedly inhibits neointima formation after balloon injury in rat carotid arteries, suggesting that CNP has multiple effects over its modest inhibitory effect on cellular proliferation. We hypothesized that local expression of CNP might have antithrombotic and antiinflammatory effects. Balloon-injured rabbit carotid arteries were infected with an adenovirus expressing human CNP (AdCNP), human tissue factor pathway inhibitor (AdTFPI), or bacterial ␤-galactosidase (AdLacZ) or infused with saline. Seven days later, shear stress-induced thrombosis was evaluated by cyclic flow variation (CFV), reflecting recurrent cycles of thrombus formation and dislodgment. CFV was observed in all AdLacZ-infected and saline-infused arteries but not in arteries infected with AdCNP or AdTFPI even in the presence of epinephrine. Injury increased the expressions of intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and infiltration of macrophages. However, these effects were markedly reduced in AdCNP-treated arteries but not in AdTFPI-infected ones. In AdCNP-infected arteries, injury-induced expression of inducible NO synthase (iNOS) was enhanced, leading to increased NO generation. Interestingly, when the enhanced NO production was inhibited, neither inhibitory effect was observed, and suppression of neointima formation by CNP was canceled. Our study demonstrates that overexpression of CNP shows antithrombotic and antiinflammatory effects and reduces neointima formation mainly through enhanced NO production.

In order to compare and clarify the effects of various antiarrhythmic drugs when given as monotherapy, we reevaluated our previous data on antiarrhythmic drugs and recalculated antiarrhythmic plasma concentrations of drugs for several canine arrhythmia models. We used three spontaneously occurring arrhythmias: a) digitalis-, b) two-stage coronary ligation-, and c) adrenaline-induced arrhythmias. All antiarrhythmic drugs of class I suppressed digitalis arrhythmia, and, except for lidocaine, also suppressed coronary ligation arrhythmia. Class II antiarrhythmic drugs, beta blockers, and class IV antiarrhythmic drugs, Ca antagonists, had common features of effectiveness and suppressed adrenaline arrhythmia in relatively low concentrations. Class III drugs were not effective on these three arrhythmias. Differences among the antiarrhythmic effects of class I drugs could not be explained by their subclassification based either on action potential duration or kinetic properties of dissociation or association with Na channels. New triggered arrhythmia models in vivo and in vitro canine hearts were developed, and drug effects were not the same as those on the three spontaneously occurring arrhythmia models.

ABSTRACT-The antiarrhythmic effects of a new class III antiarrhythmic agent, MS-551 [1,3-dimethyl-6-{2-[N-(2-hydroxyethyl)-3-(4-nitrophenyl)propylamino]ethylamino}-2,4(1H,3H)-pyrimidinedione hydrochloride], were investigated using canine coronary ligation-reperfusion arrhythmia models under slow and fast heart rate conditions and compared with those of d-sotalol. Slow and fast heart rate conditions were produced by using different anesthetics; i.e., halothane anesthesia for the slow heart rate condition and pentobarbital Na anesthesia for the fast heart rate condition. MS-551 prolonged QTc and suppressed the occurrence of fatal ventricular fibrillation (VF) on coronary reperfusion under either halothane or pentobarbital anesthesia. However, it also showed proarrhythmic effects, i.e., induction of torsades de pointes-like arrhythmia in 1 of 6 halothane anesthetized dogs before coronary ligation. d-Sotalol did not suppress the reperfusion VF in halothane anesthetized animals, nor did it show proarrhythmic effects. However, in the pentobarbital anesthetized animals, d-sotalol suppressed reperfusion VF accompanied by proarrhythmic effects in 1 of 7 dogs. d-Sotalol did not show reverse rate dependent QT prolongation. These results indicate that although both these class III drugs have similar electrophysiological properties, such as QTc prolongation, they have different antiarrhythmic effects. Also, antifibrillatory effects of class III drugs on coronary reperfusion apparently can not be explained solely by their QT prolonging effects.

No abstract

, 4-benzothiazine hydrogen fumarate, were investigated using canine models of ventricular arrhythmias, i.e. spontaneously occurring digitalis-, two-stage coronary ligation-and adrenaline-induced arrhythmias. SD-3212 suppressed adrenaline-induced arrhythmia and showed some antiarrhythmic effect on digitalis-and 48hr coronary ligation-arrhythmias. These results indicate that SD-3212 has antiarrhythmic effects common among class IV antiarrhythmic drugs and also has additional efficacy common among class I antiarrhythmic drugs, thus when considering the level of experimental arrhythmias it somewhat resembles propafenone. It may therefore become a clinically useful antiarrhythmic drug among typical class I or class IV antiarrhythmic drugs.

No abstract

No abstract