In isolated perfused guinea-pig hearts the effect of toxic concentrations of cardiac glycosides on the release of the adenine nucleotide metabolites adenosine, inosine, hypoxanthine, xanthine, and uric acid was investigated. Digoxin concentrations of 0.03-1 mumol.l-1 produced moderate to severe tachyarrhythmias. Large amounts of metabolites were released by concentrations of 0.1 mumol.l-1, and higher. Occurrence of glycoside-induced ventricular fibrillation was associated with a particularly high release. Metabolite release was also obtained when fibrillation was elicited electrically in normal control hearts, or in hearts receiving simultaneously a marginally toxic digoxin concentration (0.03 mumol.l-1). Digoxin-induced tachyarrhythmias and metabolite release were almost completely prevented by a high potassium concentration in the coronary perfusion fluid (8.1 mmol.l-1). The antiarrhythmic effect was also obtained with lidocaine (60 mumol.l-1), but the release was only partially antagonized. Similar results concerning arrhythmias and metabolite release as with digoxin were obtained with ouabain. The findings suggest that the decrease in myocardial ATP observed in glycoside-intoxicated heart preparations is partly due to the loss of nucleotide precursor substances. Moreover, it appears likely that liberated adenosine in the interstitium of severely intoxicated heart preparations reaches pharmacologically effective concentrations.

Adenine Nucleotides↗

PubMedDate not supplied

Immunopathological findings in posterior scleritis.

Posterior scleritis can present with a variety of symptoms, and its clinical diagnosis is therefore difficult. Little is known about the pathogenesis and the cellular effector mechanisms. This case report presents the immunopathological findings of posterior scleritis in the enucleated eye of a 28-year-old female with no known underlying disease. The cells infiltrating the scleral fibers consisted predominantly of T cells. Many of them were CD4 cells. Clusters of T and B cells were found in perivascular areas. No signs of primary vasculitis were seen. The cellular infiltrate in posterior scleritis shows features compatible with a T-cell-mediated (autoimmune) disorder.

Adult↗

PubMedDate not supplied

Antiarrhythmic and antinecrotic effects of yohimbine stereoisomers in rats during coronary occlusion and reperfusion.

In pentobarbital-anesthetized rats the left coronary artery was ligated for 5 or 30 min and then opened for reperfusion of the ischemic myocardial area. Twelve min prior to the coronary occlusion yohimbine stereoisomers, namely corynanthine and rauwolscine, or saline solution were given intravenously. In the saline controls both ischemia and reperfusion provoked severe tachyarrhythmias with ventricular fibrillation in 37.5% or 54.6%, respectively. Using corynanthine and rauwolscine a highly significant antiarrhythmic effect was observed. Corynanthine completely prevented ventricular fibrillation and delayed significantly the development of myocardial necrosis. The factors likely underlying the antiarrhythmic and antinecrotic effects are discussed.

Animals↗