Submitted on September 26, 2003
Accepted on February 2, 2004
Transfer function analysis of heart rate variability in response to water intake: correlation with gastric myoelectrical activity
C.L. Chen1, H.H. Lin1, William C. Orr2, Cheryl C.H. Yang3, and Terry B.J. Kuo4*
1 Department of Medicine, Tzu Chi University, Hualien 970, Taiwan; Department of Gastroenterology, Tzu Chi Buddhist General Hospital, Hualien 970, Taiwan
2 Lynn Institute for Healthcare Research, Oklahoma City, OK, USA
3 Department of Physiology, Tzu Chi University, Hualien 970, Taiwan
4 Institute of Neuroscience, Tzu Chi University, Taiwan; Department of Neurology, Tzu Chi Buddhist General Hospital, Taiwan
* To whom correspondence should be addressed. E-mail: tbjkuo{at}ms33.hinet.net.
We utilized transfer function analysis of heart rate variability (HRV) and respiration to investigate the effect of water intake on gastric myoelectrical activity and its relationship to vagal activity. The electrogastrography (EGG) and HRV were recorded simultaneously before and after drinking 500 ml water in 10 healthy subjects. We observed good linearity between lung volumes and HRV signals at ventilatory rate between 0.2 and 0.4 Hz before and after water intake. The EGG-3 cycles per minute (cpm) power increased remarkably after the water intake. We found that there was a significant increase in the magnitude of the respiration-HRV transfer function after water intake (P < 0.05). The EGG-3 cpm power was positively correlated with the transfer magnitude throughout the study (r = 0.54, P = 0.01). These results confirm that transfer function analysis of HRV sensitively identifies subtle changes in the respiratory sinus arrhythmia that occurs with water intake. The present findings suggest that transfer function analysis of HRV and respiration after water intake can be used to evaluate vagal nervous activity in the human gut.
