Abstract
Purpose : The importance of nicotinamide dose on inducing blood pressure changes in mice and humans was investigated. Methods and Materials : Blood pressure measurements in human volunteers were made using an inflated cuff procedure after oral ingestion of 3 or 6 g nicotinamide. Animal blood pressure measurements were performed in fully awake nonanesthetized female CDF1 mice, 24 h after cannulation of the carotid artery. Results : In humans, the average (± 1 SE) resting systolic and diastolic pressures were 122.8 mmHg (± 2.5) and 80.6 mmHg (± 2.1), respectively. They were unchanged during the first 3 h after ingestion of either 3 g or 6 g nicotinamide. The resting value (± 1 SE) in mice was 115.1 mmHg (± 4.0) and this was significantly reduced following intraperitoneal injection of 400–1000 mg/kg nicotinamide. This decrease was maximal within 15–30 min after injection and was linearly dependent on drug dose. At doses of 200 mg/kg or less, no significant effect on blood pressure was observed. Conclusion : Doses between 100–200 mg/kg in mice are known to be equivalent to 6 g in man and can also produce maximal radiosensitization in murine tumors. Our results, therefore, not only show that the mouse and human data are entirely consistent, but also suggest that nicotinamide-induced decreases in blood pressure are not necessary for radiosensitization.
Published Version
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