The effects of intravenous injection of purified rabbit apoA-I on the progression of aortic atherosclerosis in cholesterol-fed rabbits were examined. In experiment 1, 28 rabbits were equally divided into groups A and B and fed a 0.5% cholesterol diet for 90 days. For the last 30 days, group B received 40 mg apoA-I every week. The fatty streak lesions in group B (23.9 +/- 15.6%) were significantly suppressed compared with those in group A (46.0 +/- 24.9%) (P < .05). In experiment 2, 33 rabbits were divided into four groups (8 or 9 rabbits per group) and fed a 0.5% cholesterol diet. Group A was killed on day 105, while groups B, C, and D were maintained for an additional 60 days on a normal diet, during which time groups C and D received 1 mg apoA-I every other day or 40 mg apoA-I every week, respectively. The lesions in group C (70.2 +/- 15.4%) and group D (65.7 +/- 20.0%) were significantly suppressed compared with those in group B (86.2 +/- 13.7%) (P < .05) but were not reduced to the level of group A (50.0 +/- 22.9%). Although apparent regression was not observed under these conditions, the present study provided the first evidence for the antiatherogenic effect of homologous and apoA-I on the progression of atherosclerosis in cholesterol-fed rabbits.

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Rabbits that were injected intradermally with pertussis toxin (PT), produced from Bordetella pertussis, showed slight edema and erythema at the injection sites, but not hemorrhage nor necrosis. The edema lesions were stained blue by the intravenous injection of Pontamine Sky Blue 6B dye, suggesting that PT caused increased vascular permeability, similarly to the permeability factor (PF) of cholera toxin. The reaction of the PF of PT could be determined by measuring the diameter of the blue area. The diameter of the blue area bore a good linear relationship to the logarithm of the dose of PT. The activity of the PF was neutralized by anti-PT rabbit serum. Detoxification of PT with formalin did not increase the vascular permeability, but reverted pertussis toxoid showed a PF reaction in proportion to the reverted leukocytosis-promoting and histamine-sensitizing activities of PT. The supernate of a Bordetella pertussis culture also induced a PF reaction and the reaction could be made clear by heating the supernate at 56 C for 30 min, but the supernate of Bordetella bronchiseptica did not induce the reaction at all.Pertussis toxin (PT) also called leukocytosis-promoting factor (8), histaminesensitizing factor (11), islet-activating protein (16), or pertussigen (1), is a protein toxin produced by Bordetella pertussis. It elicits various biological effects in mammals, and is shown to be an important protective antigen for mice against both intracerebral (10) and aerosol challenges (12) with virulent Bordetella pertussis.Recently we found that PT increases the vascular permeability of skin capillaries similarly to the permeability factor (PF) of cholera toxin (CT) (4) and the PF of PT shows a good correlation with the dose of PT. Munoz et al (9) reported that vascular permeability in the striated muscle of mice is increased by injecting PT intravenously (iv) ; however the PF of PT was not studied. Therefore, we examined histological changes in the skin tissues at the PT injection sites and showed that the PF reaction is one of the biological activities of PT.A variety of methods for assaying PT are known (6,8,11,16), but some problems, such as lack of simplicity, inaccuracy, and high cost remain. We found that the use of PF of PT is a simple and accurate method to determine the biological activity of PT.