Determination of the effects of urination on sympatho-vagal balance by heart rate variability

Aim: Act of urination is a physiological process requiring sympathetic and parasympathetic (vagal) interactions. Heart rate variability (HRV), a non-invasive technic investigating the variation in duration of the sequential heart beats, provides information about sympatho-vagal balance. The aim of the current thesis was to study the effects of sympatho-vagal interactions occurring during urination on HRV parameters. Material and method: Following ethical consent, 40 apparently healthy males, aged 18-30 years, participated to the current study. For the measurement of HRV, 90 seconds electrocardiogram (ECG) recordings were carried out for 6 sequential stages at sitting position as follows: at urge to urinate stages [sitting in the room (1) and at the water-closet (2)], at urination stage [at water-closet (3)] and following urination [at water-closet (4), immediately after in the room (5), and 20 min after the urination, in the room (6)]. Additionally, all data were standardized to each participant's duration of urination (10-88 sec). HRV parameters included time- (HR, SDNN, RMSSD, pNN50, %CV) and frequency-domain (TP, VLF, LF, HF, LF/HF) parameters. Results: HR, SDNN and %CV values increased significantly at the time of urination but RMSSD increased during urination (p<0.05). However, pNN50 decreased significantly following urination (p<0.05). While HF (ms2) decreased during urination, LF/HF increased during urination (p<0.05). There were no changes in parameters like LF (ms2) and TP (p<0.05). Conclusion: In this thesis, HRV was studied in detail during urination process. As there were significant changes in HRV parameters at the various stages of urination, it was concluded that basic physiological information regarding autonomous control of urination might be obtained by reinterpreting non-invasive HRV technic.