ON THE EFFECT OF CAFFEINE ON THE AUTONOMIC REGULATION OF THE BLOOD CIRCULATION SYSTEM

Abstract

Caffeine is one of the most famous substances in the world. The drug is studied in healthy individuals and patients of different ages and gender, under stress and physical exercises, in a wide range of doses and at different times after the administration. There is no clear answer in the literature how it affects the ratio of sympathetic and parasympathetic regulation in the body. Therefore, it is of interest to clarify the effect of caffeine on the autonomic regulation of blood circulation in young healthy volunteers. Research purpose was to study the effect of a single average therapeutic dose of caffeine-sodium benzoate on the Kerdo vegetative index and to assess changes in the tone of the autonomic nerve system. Object and research methods. The study involved 36 volunteer students aged 20-22 years, among them, 20 men and 16 females. The composition of the groups was formed stochastically. All participants were healthy, had no contraindications for caffeine intake and gave their informed consent. They took 1 tablet (200 mg) of caffeinesodium benzoate. Before taking the drug and 40 minutes after it, the respiratory rate, heart rate (HR) and blood pressure (BP) were determined by conventional methods. The Kerdo vegetative index (VI) was calculated. The obtained data were processed using standard computer programs Statistica for Windows 8.0. In relation to the frequency of positive or negative values of VI, the nonparametric criterion “Fisher’s exact method” (TMF) was used. Research results and discussion. Before taking caffeine- sodium benzoate, the respiration rate, HR and BP in all study participants were within normal limits and did not differ in men and women. The average values of VI in both men and women were negative and did not differ significantly, that indicated the predominance of parasympathetic regulation. After taking the drug, an increase in systolic and diastolic BP was observed in males (p <0.05). In this case, HR and respiratory rate did not change compared to the initial level. VI remained negative, but increased in absolute value (p <0.05), which can be regarded as an increase in parasympatheticotonia and its role in the regulation of blood circulation. After taking caffeine-sodium benzoate in women, only an increase in systolic BP was noted (p <0.05). Under the influence of caffeine, gender differences appeared in the respiration rate and VI, which after administration of the drug were lower (p <0.05) in females. A more intense increase in parasympatheticotonia in men was also confirmed by a greater frequency of an increase in the absolute values of negative VIs and (or) their appearance at the place of positive and zero indices (p TMF <0.025) compared to that in women. Thus, with the random formation of groups for a clinical study, it is possible that people prevail in them with the prevalence of one or another part of the autonomic nerve system (in our case, parasympatheticotonia). The increase in the parasympathetic effect in the blood circulation system under the action of caffeine in male volunteers, obviously, reflects the more pronounced activating effect of this substance on the vagus nerve centre on the basis of initial parasympatheticotonia. Conclusion. The results obtained suggest that in studies of the effects of caffeine and its salts on humans, groups should be randomized not only by gender, but also by the state of autonomic regulation, for example, based on the Kerdo VI.

Keywords

• caffeine
• heart rate
• blood pressure
• vegetative index
• parasympatheticotonia