The article deals with experimental studies of non-linear male and female rats aged 3.5-5 months in I, II, and III types of weather. The objective was to investigate the mechanisms of adrenergic and cholinergic blockers’ effect in progressive adrenalineinduced heart damage in different weather types. Controlled ECG were registered in 30 min following anapryline or atropine injection, and 30, 60 and 180 min following adrenaline injections. The cardiac rhythm variability was studied. The percentage deviations of mode indices (Mo), mode amplitude (AMo) and variation ranges (Õ) compared to absolute control values, were calculated. Adrenaline-induced heart damage was caused by a single intraperitoneal injection of adrenaline solution. Blockage of -adrenoreceptors was provided with intraperitoneal injection of anapryline solution (1.5 mg/kg). Blockage of M-cholinergic receptors was induced by intramuscular injection of atropine solution (1 mg/kg). The weather type data were taken from daily weather reports by the Ternopil regional meteorological station.
All manipulations and methods of slaughtering animals met the requirements and principles of “European Convention for the Protection of Vertebrate Animals used for Experimental and Other Scientific Purposes” (Strasburg, 1985) adopted by the I National Congress on Bioethics (Kyiv, 2001).
Adrenaline administration intensified by anapryline action was noted to cause animal death, it depending on gender and weather type. The animal mortality was not found in Type II weather, which is the most typical weather pattern for Ternopil. The rats might have become adapted to it. Death among female rats in Type I weather and male rats in Type III weather was registered in 10–15 min after adrenaline administration, whereas the female rats’ death in Type III weather was reported in an hour. All the three animal groups demonstrated considerable deviations in Õ indices.
The activity of parasympathetic portion of the autonomic nervous system (ANS) in female rats increased by 68% in Type I weather, whereas in male rats it raised by 53% in Type III weather. Hence, a considerable cholinergic influence on the heart was observed to increase before administering adrenaline. Adrenaline injection most probably potentiated anapryline effect, and caused bradycardia aggravation as well as cardiac arrest. In Type III weather, female rats demonstrated an increase and a subsequent decrease in the effect of parasympathetic portion of the ANS on the cardiac activity. The animal mortality in this group occurred within one hour following adrenaline injection. Õ index was reduced by 53% over 30 to 60 min period after adrenaline administration. A considerable reduction in the cardiac vagal influence resulted in animal death. Thus, severe increase or decrease in cholinergic mechanisms regulation in rats contributed greatly to pronounced autonomic imbalance and animal mortality.
In blockage of M-cholinergic receptors, death among male rats in Type III weather occurred within 10–15 min after adrenaline injection. According to heart rate autonomic regulation indices, the cardiac vagal influence was revealed to decrease by 30% in 30 min after atropine injection and by 43% in 30 min after adrenaline administration. Pronounced imbalance in the ANS regulation might have caused animal mortality. The reduction in cholinergic regulation is considered to be its main reason.
The obtained findings proved the rats possess higher parasympathetic tone of the ANS. Adrenergic and cholinergic receptors’ reactivity varied depending on the weather type. The maximal reactivity was noted in male rats in Type III weather and in female rats in Type I weather, minimal – in all animals in Type II weather.
Full text: PDF (Ukr) 154K