Abstract

Histidine is an aminoacid of high affinity towards singlet oxygen to cause its elimination, capable of chelating transition metals, which catalize generation of hydroxyl radical of extremely high destructive potency. Antioxidative properties of histidine have been empolyed in cardioprotection during ischemia and reperfusion of the heart. The study aimed to assess the effect of histidine on heart rate variability (HRV). The HRV analysis is established method of a non-invasive diagnostics of the way autonomic nervous system influence heart rate (HR). HRV analysis is used in practive for evaluation the risk of critical heart arrhytmia. The experiments were performed on 8 unanaesthetized and unrestrained rats (320 – 395 g), surgically instrumented, which were challenged with increasing doses of histidine (30 – 750 mg/kg) administered intravenously. ECG was continuously recorded to extract periodograms of consecutive RR segments, and than to assess timing of the following heart cycles.Spectral analysis based on the algorithm of the fast Fourier transformation (FTT) was employed to compare HRV before and during subsequent infusions of increasing histidine concentrations. HRV variables were computed: total spectral power (TSP), low frequency power (LF, within the frequency range of 0,28 to 0,74 Hz), and high frequency power (HF, within the frequency range of 0,74 to 2,2 Hz). Histidine significantly accelerated HR and also substantially enhanced TSP (from od 191,2 ± 49,6%; do +313,6 ± 94,5%, depending on the dose). The ratio LF/HF was found significantly increased due to histidine (from 0,436 ± 0,153 up to 1,070 ± 0,295 – dose of 250 mg/kg), that indicates enhanced role of sympathetic component in the heart rhytm regulation. Such profile of regulatory effects of histidine is potentially deleterious, since it promotes severe cardiac arrhythmias.

Adres: dr Tomasz Wierzba
Katedra i Zakład Fizjologii AMG
ul. Dębinki 1, 80-211 Gdańsk
tel. +58 3491475
e-mail: twierzba@gumed.edu.pl