Abstract
Pharmacological effects of thiamine and its derivatives on the central nervous system, particularly on its part regulating the blood pressure were studied and the following results were obtained:
1) The blood pressure rose on an average to 48 and 30 mmHg at a dosis of 20 and 10 mg thiamine hydrochloride, respectively, whereas the mean pressure rise with an admini-stration of 10 mg thiamine diphosphate was 41 mmHg.
2) When combined with antihistaminics, neither the administration of thiamine hydro-chloride nor that of thiamine diphosphate raised the blood pressure.
3) For the effect of thiamine to raise the blood pressure, tachyphylaxis was recognized.
4) Histamine was estimated quantitatively using a piece of small intestine from guinea pig. Administration of 20 and 10 mg of thiamine hydrochloride gave 10-8 and 10-8 to 10-10 g/ml histamine, respectively, whereas 10 mg thiamine diphosphate resulted in 10-9 to 10-10 g/ml.
5) The effluence of cereblospinal fluid was subjected to fluorescence monochromator after it was treated by the Shore's method. Activation with 320mμ gave a peak fluorescence of 420 mμ, identifying histamine.
6) It seems very likely that the rise of the blood pressure associated with the administration of thiamine in the lateral ventricle was caused by histamine that was released by mast cells of hypophysial stalk and posthypophysis so that the compound reacted with intraventricular chemoreceptors.
