Fatty Acid Supplementation Affects Skin Wound Healing in a Rat Model.

Polyunsaturated fatty acids (PUFA) play an important role in reparative processes. The ratio of PUFAs n-3 to n-6 may affect wound healing. The study aimed to evaluate the effect of dietary supplementation with n-3 and n-6 PUFA in two proportions on skin wounds in laboratory rats. Adult male Wistar rats received 20% fat emulsion with a ratio of 1.4:1 (group A) or 4.3:1 (group B) for n-3:n-6 PUFAs at a daily dose of 1 mL/kg. The control group received water under the same conditions. The animals were supplemented a week before and a week after the skin excision performed on the back. The level of wound closure, various parameters of oxidative stress, and plasma fatty acids composition were evaluated. Wound tissue samples were examined by electron microscopy. The administration of fat emulsions led to significant changes in plasma polyunsaturated fatty acid composition. The increased production of reactive nitrogen species, as well as more numerous newly formed blood vessels and a greater amount of highly organized collagen fibrils in both groups A and B may indicate more intensive healing of the skin wound in rats supplemented with polyunsaturated fatty acids in high n-3:n-6 ratio.

Haloperidol affects coupling between QT and RR intervals in guinea pig isolated heart.

Prolonged QT interval is an independent risk factor for development of ventricular arrhythmias. Haloperidol is one of the drugs inducing QT prolongation. Previous studies showed that haloperidol affects not only QT duration but also heart rate (RR interval). The present work focused on relationship between QT and RR and its changes under acute and chronic haloperidol administration. The study included 14 male guinea pigs divided into control and haloperidol-treated group. After 21-days administration of haloperidol or vehiculum, electrograms in isolated hearts were recorded. QT/RR and dQT/dRR coupling were calculated. Chronic haloperidol administration significantly decreases the coupling between QT and RR. Acute haloperidol exposure significantly decreases the dQT/dRR coupling in both treated and untreated guinea pig hearts. Flatter QT/RR relationship reveals a lack of QT adaptation to increased heart rate. It should be emphasized that in such situation ECG recording will not show significant QT prolongation evaluated according to clinical rules. However, if QT interval does not adapt to increased heart rate sufficiently, the risk of ventricular arrhythmias may be increased despite practically normal QT interval length. The results are supported by findings in biochemical analyses, which proved eligibility of the used model.

Effect of increased left ventricle mass on ischemia assessment in electrocardiographic signals: rabbit isolated heart study.

BACKGROUND: Detailed quantitative analysis of the effect of left ventricle (LV) hypertrophy on myocardial ischemia manifestation in ECG is still missing. The associations between both phenomena can be studied in animal models. In this study, rabbit isolated hearts with spontaneously increased LV mass were used to evaluate the effect of such LV alteration on ischemia detection criteria and performance. METHODS: Electrophysiological effects of increased LV mass were evaluated on sixteen New Zealand rabbit isolated hearts under non-ischemic and ischemic conditions by analysis of various electrogram (EG) parameters. To reveal hearts with increased LV mass, LV weight/heart weight ratio was proposed. Standard paired and unpaired statistical tests and receiver operating characteristics analysis were used to compare data derived from different groups of animals, monitor EG parameters during global ischemia and evaluate their ability to discriminate between unchanged and increased LV as well as non-ischemic and ischemic state. RESULTS: Successful evaluation of both increased LV mass and ischemia is lead-dependent. Particularly, maximal deviation of QRS and area under QRS associated with anterolateral heart wall respond significantly to even early phase (the 1st-3rd min) of ischemia. Besides ischemia, these parameters reflect increased LV mass as well (with sensitivity reaching approx. 80%). However, the sensitivity of the parameters to both phenomena may lead to misinterpretations, when inappropriate criteria for ischemia detection are selected. Particularly, use of cut-off-based criteria defined from control group for ischemia detection in hearts with increased LV mass may result in dramatic reduction (approx. 15%) of detection specificity due to increased number of false positives. Nevertheless, criteria adjusted to particular experimental group allow achieving ischemia detection sensitivity of 89-100% and specificity of 94-100%, respectively. CONCLUSIONS: It was shown that response of the heart to myocardial ischemia can be successfully evaluated only when taking into account heart-related factors (such as LV mass) and other methodological aspects (such as recording electrodes position, selected EG parameters, cut-off criteria, etc.). Results of this study might be helpful for developing new clinical diagnostic strategies in order to improve myocardial ischemia detection in patients with LV hypertrophy.