Abstract
The hemodynamic effects of sublingual nitroglycerin were examined at rest and during 70° head-up tilt. The twenty-eight healthy male normotensives and the fifty-one male hypertensives were investigated for evaluating the cardiovascular regulation in the presence of high blood pressure and aging. Both the normotensives and the hypertensives were divided into three age groups as the previous report. The hypertensives in the young group were subdivided into the borderline and the established hypertensives. 70° head-up tilt test was made before and after administration of nitroglycerin. Each subject was first tilted for five minutes and returned to the supine position for five minutes. A fresh 0.3mg nitroglycerin tablet was then administered sublingually and 70° head-up tilt test was repeated after five minutes. Hemodynamic parameters were measured in the same way as previously reported. The effects of nitroglycerin were examined in the supine position five minutes after administration and in the first minute of tilted position. Compared with the state before nitroglycerin, following results were obtained.
A) Hemodynamic changes in the supine position five minutes after nitroglycerin.
1) Heart rate increased in almost all the cases and especially in the borderline hypertensives.
2) As to blood pressure, systolic BP tended to fall and there was slight increase of diastolic BP. The old hypertensives showed significantly greater fall in systolic BP than the normotensives.
3) There was tendency to increase in TPR and to decrease in SV and CO.
4) Abbreviation of QS2-I and ETI, lengthened PEP, and heightened PEP/LVET ratio were observed.
B) Hemodynamic changes in the first minute of tilted position five minutes after nitroglycerin.
1) The increase in heart rate was greater than the state before administration and there was significant correlation between before and after nitroglycerin. The borderline hypertensives showed greater increase in heart rate than the normotensives.
2) After nitroglycerin, systolic and mean BP tended to fall but nitroglycerin had various effect on diastolic BP. Significant correlation was observed between the fall in systolic BP and age. In the old hypertensives, this fall in systolic BP was significantly greater than in the normotensives.
3) Compared with the state before administration, TPR tended to decrease, CO changed a little and SV decreased.
4) As to STI compared with the period before nitroglycerin, QS2-I and ETI tended to shorten. In the young and the middle-aged normotensives, PEP tended to shorten but changed a little in the other groups. PEP/LVET ratio tended to increase except in the young normotensives.
