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The susceptibility to ventricular arrhythmias under the conditions of cardiac ischemia and reperfusion was investigated in the Langendorff heart preparation of rats fed for eight weeks a standard chow enriched with 2% of pulverized wild garlic leaves. The isolated hearts were perfused with a modified Krebs-Henseleit solution. The incidence of ventricular fibrillation (VF) during 20 min occlusion of the descending branch of the left coronary artery (LAD) was significantly reduced in the wild garlic group as compared to untreated controls (20% vs 88%). The same holds for the size of the ischemic zone (33.6% vs 40.9% of heart weight). In the reperfusion experiments (5 min after 10 min ischemia), ventricular tachycardia (VT) occurred in 70% of the wild garlic group vs 100% in untreated controls and VF in 50% vs 90%. The time until occurrence of extrasystoles, VT or VR was prolonged. No significant alterations in cardiac fatty acid composition could be observed. Although the prostacyclin production was slightly increased in hearts of the wild garlic group, inhibition of cyclooxygenase by acetylsalicylic acid (ASA; aspirin) could not completely prevent the cardioprotective effects suggesting that the prostaglandin system does not play a decisive role in the cardioprotective action of wild garlic. Furthermore, a moderate angiotensin converting enzyme (ACE) inhibiting action of wild garlic was found in vitro as well as in vivo that could contribute to the cardioprotective and blood pressure lowering action of wild garlic. Whether a free radical scavenging activity of wild garlic is involved in its cardioprotective effects remains to be established.

The protective effect against reperfusion arrhythmias of a 3-month oral pretreatment with a dried extract of Crataegus oxyacantha (LI 132)(standardized to 2.2% flavonoids) was studied with the Langendorff heart of the rat after global no-flow ischemia. The heart was perfused with a modified Krebs-Henseleit solution in which the K+ content was reduced to 3.4 mmol/l in order to lower the fibrillation threshold. According to pilot experiments which considered various durations of global no-flow ischemia ranging from 10 to 20 minutes, two durations were chosen for the present study: 20 minutes (group 20) in which ventricular fibrillation (VF) was the predominant form of arrhythmias, and 18 minutes (group 18) in which the prevalence of VF was markedly lower despite the small difference in the duration of ischemia. Crataegus pretreatment significantly (p = 0.02) reduced the average prevalence of malignant arrhythmias (VF + Flutter) as observed during the 20-min-period of reperfusion as follows: group 20: from 89% (control, n = 9) to 51% (LI 132, n = 7), group 18: from 48% (control, n = 8) to 8% (LI 132, n = 8). In group 20, ventricular tachycardia (VT) could be observed only in the treated group, because of the predominance of VF in the control group. LI 132 pretreatment reduced the average prevalence of VT in group 18 in spite of the identical percentage of occurrence (6 out of 8 rats, with and without treatment) due to a shorter duration of the VT episodes. Thus, under the conditions of our experiments, effective prevention against reperfusion arrhythmias by Crataegus pretreatment was evident.

It was the aim of this study to investigate (1) whether preconditioning modifies the fatty acid (FA) composition of myocardial phospholipids (PL), (2) whether a previous modification of membrane PL composition by the administration of coconut oil or fish oil influences the preconditioning, and (3) to compare the protective effects of preconditioning to those of dietary fish oil. To this end, three groups of rats were given during 10 weeks either a standard diet, or a standard diet + 10% coconut oil, or a standard diet + 10% fish oil. The preconditioning was performed in situ in the anesthetized open-chest rats by 2 cycles of 3 min left anterior descending coronary artery occlusion and 10 min reperfusion. It was followed by a 40 min ischemia and a 60 min reperfusion. ECG was recorded and used for the continuous count of the salves of extrasystoles, ventricular flutter and fibrillation. These rhythm disturbances were subsequently added and evaluated as total arrhythmias. The FA of tissue PL were analyzed in a sample of the ischemic zone the size of which was determined by means of malachite green. Coconut oil diet (rich in saturated FA) modified slightly the myocardial PL by increasing oleic acid and decreasing linoleic acid and resulted in the highest incidence of arrhythmias. Fish oil diet had the opposite effect in modifying drastically the PLFA (replacement of the n-6 FA by the n-3 FA) and minimizing significantly the arrhythmias in comparison with the standard diet group.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of long-term dietary application of garlic (dried powder, 0.5% in weight of standard chow; G group) or linseed oil (2.5%; L group) as well as a combination of both interventions (L + G group) on the life span of hypertensive rats (SHR SP) was investigated. A further group fed with standard chow served as control (C). The dietary interventions were started at the age of three weeks. Besides regular measurements of the systolic arterial blood pressure (oscillometrically at the tail artery) as well as of heart rate and body weight, autopsy and histological investigations were performed. Both diets, and particularly their combination, prolonged life span significantly (mean values (days) C: 434.5 +/- 23.5; G: 453.2 +/- 16.2; L: 470.0 +/- 26.2; L + G: 494.8 +/- 39.2). There was no significant interaction of the factors garlic and linseed oil. Systolic blood pressure as measured during the compensatory stage (data used until the 39th week of life) was significantly lowered by both garlic (mean -5.8 mm Hg), linseed oil (mean -6.3 mm Hg), and their combination (mean -11.3 mm Hg). The animals died as a consequence of congestive left and right ventricular failure with ventricular hypertrophy, dilatation, myocardial fibrosis and cellular infiltration, left ventricular atrial thrombosis (in most cases), and terminal pneumonia. On the other hand, arteriosclerotic plaques and signs of cerebral stroke could not be detected. Except for the degree of hypertrophy, which was lower in the treated groups, no differences were obvious regarding the morphological findings at the time of death. There was a significant positive correlation between mean blood pressure and the degree of left ventricular hypertrophy. Furthermore, a significant negative correlation between mean blood pressure and ventricular hypertrophy on the one hand and survival on the other hand was obvious provided the total number of animals was considered, however, not within the individual groups. The same applies to the relation between the reduction of left ventricular hypertrophy and life span. The relatively slight hypotensive effect of both dietary interventions as well as the results of previous investigations speaks in favor of a substantial influence of factors independent of blood pressure. In view of controversial results and interpretations in international literature, the mechanisms involved need further study.