Heart Rate and Serum Nitric Oxide Express Circahoralian Oscillation in Hypertensive Patients

Abstract

Cardiovascular cells possess circadian oscillators and certain cardiovascular diseases are attributed to disruption in cardiac circadian rhythm. This study is aimed to find the association between the serum level of nitrogen species and the electrocardiograph records taking in consideration the circahoralian oscillation in hypertensive patients. A total number of fifty hypertensive patients and twenty healthy subjects were admitted in this study. The anthropometric measurements and lipid profile were determined. Serum nitric oxide and peroxynitrite were measured at the same time of electrocardiograph (ECG) records twice over a period of 60 min. The mean values of baseline record of electrocardiograph parameters non-significantly differed from corresponding values of healthy subjects. Hypertensive patients showed significant (p < 0.05) decrease in sinus heart rate in second record (74.202 ± 20.768 beat/min) compared with the first record (80.494 ± 12.266 beat/min). In hypertensive patients, the mean serum nitric oxide levels decreased to 60% of the mean value of healthy subjects while peroxynitrite increased by four fold of healthy subjects. The significant oscillation in heart rate over 60 min, at rest, is associated with significant changes in nitrogen species levels. It concludes that circahoralian (ultradian) rhythm existed in hypertensive patients in term of simultaneous oscillation in heart rate and nitrogen species.

Keywords: Hypertension, heart rate, nitrogen species, circahoralian oscillation