Rabbit aortic histamine synthesis following short-term cholesterol feeding.

The histidine decarboxylase (HD) activity of thoracic and abdominal aortic segments obtained from male, Dutch-belted rabbits fed a diet containing 0.5 per cent cholesterol for periods of either 2 or 4 weeks was examined. Mean thoracic aortic HD activities, expressed as histamine-forming capacity (HFC), were 3911 plus or minus 492, 6254 plus or minus 656, and 6215 plus or minus 878 dpm/100 mg benzenesulfonylhistamine (BSH) for the control group and from rabbits fed cholesterol for 2 and 4 weeks, respectively. Both treatment means were significantly higher than the control (P smaller than 0.05). Similar examination of abdominal aortic HD activities yielded mean HFC's of 4029 plus or minus 399, 5694 plus or minus 521, and 4762 plus or minus 902 dpm/100 mg BSH for control animals and those of the 2- and 4-week treatment groups, respectively. The difference between mean HFC's of the control and 2-week treatment group was significant (P smaller than 0.05). All increases occurred in the absence of either aortic structural alterations or any lipid deposition. These results give credence to the concept that the atherogenic process represents, at least in part, a delayed-prolonged inflammatory response phenomenon of the arterial wall.