[Experimental investigations on the tumorigenic activity of cigarette smoke condensate on mouse skin. VII. Comparative studies of condensates from different modified cigarettes (author's transl)]. / Experimentelle Untersuchungen über die tumorerzeugende Wirkung von Zigarettenrauch-Kondensaten an der Mäusehaut. VII. Einzelvergleiche von Kondensaten verschiedener modifizierter Zigaretten.

Condensate from different modified cigarettes were compared with condensate from a standard cigarette with regard to its tumorigenic activity on mouse skin. Significant lower effects were observed in test series with cigarettes from expanded tobacco. Different results were obtained in experiments with cigarettes from the new smoking materials. In one case the effect was higher, in two another cases the effect was lower in comparison to the effect of condensate from reference cigarettes. A certain influence may be referred to the diameter of the cigarette, i.e. a thinner cigarette shows a lower biological effect. The lowest tumoringenic effect was observed in tests with cigarettes with a high content of Burley-stems.

Investigations of cigarette smoke dosages in inhalation experiments with Syrian hamsters. I. Concentration of cigarette smoke in the inhalation chamber and of carbon monoxide in the blood.

We tested 20 different smoke inhalation machines and determined that 60% of the gas phase and 40% of the total paritulate matter reached the inhalation chamber; the remainder was lost in the exhaust gases. After determining these concentration percentages, we were able to calculate precisely the dosage of each puff of smoke administered to Syrian hamsters in our smoking machine. We also determined that the CO-Hb content in the blood of the hamsters rose to 60%; this CO-Hb value was a limiting factor for time of exposure to smoke, since too-high concentrations of CO-Hb would have killed the animals. On the basis of these results, we concluded that the animals should be exposed as long as possible to attain a high dose of smoke, but because of toxic effects the exposure time should not exceed 20 minutes, and the CO-Hb content should not exceed 60%.

Investigations of cigarette smoke dosages in inhalation experiments with Syrian hamsters. II. Uptake of cigarette smoke by the animals; comparisons of the influence of the gas phase and the whole smoke of different cigarettes.

An increased CO2 content (CO2 enrichment) in the smoke-air mixture was measured in an inhalation chamber containing Syrian hamsters. Since these additional CO2 concentrations originated from the animals' expiratory air, the level of CO2 (CO2 enrichment) was considered a function of the respiratory capacity. Results obtained with this method of characterizing the respiratory behavior of hamsters in inhalation experiments led us to conclude that the vapor phase of cigarettes reduced respiration up to 45% and the whole smoke, up to 60%. Qualitative and quantitative differences in the composition of the vapor phase and particulate phase as offered in animal inhalation experiments for comparing different cigarettes did not induce measurable differences in the respiratory behavior. Therefore, such inhalation experiments were found to be suitable for comparing the relative effects of different cigarette types. Estimations on the inhaled amounts of TPM led to results that were similar to those obtained in experiments with radioactively labeled smoke.

[Effect of nicotine in pigs (author's transl)]. / Die Wirkung von Nikotin beim Schwein

18 pigs in which venous catheters were positioned for long-term use were injected with nicotine in physiological saline: group 1: 1 mg without anaesthesia; group 2: 1 mg/animal, Hypnodil-anaesthesia; group 3: 0.0143 mg/kg body weight, Hypnodil-anaesthesia. The dose of 1 mg is corresponding to that amount of nicotine contained in the main smoke of a commercially used cigarette. The dose of 0.143 mg/kg body weight is calculated per 1 kg body weight assuming that a man of 70 kg body weight resorbes the total amount of nicotine (1 mg) after maximum inhalation. Application of 1 mg induced the following alterations: sino-auricular block, AV-block of first and second degree, asystolia up to 2 seconds, short decrease in blood pressure and bradycardia as well as flattening and/or inversion and biphasic reaction of T. A longer lasting increase in blood pressure was observed in non-anaesthesized animals. Animals treated with 0.0143 mg/kg body weight showed AV-block of first degree with subsequent extrasystoles. Blood pressure, heart rate and T-wave showed no alterations. Decisive for the induction and extent of acute disturbances seems to be the dose of nicotine. Therefore, a decrease of the nicotine content seems to be indicated toward a "less harmful cigarette".

[Experimental studies on tumorigenic activity of cigarette smoke condensate on mouse skin. V. Comparative studies of condensates from different modified cigarettes (author's transl)]. / Experimentelle Untersuchungen über die tumorerzeugende Wirkung von Zigarettenrauch-Kondensaten an der Mäusehaut. V. Mitteilung: Einzelvergleiche von Kondensaten verschiedener modifizierter Zigaretten

The tumorigenic effect of smoke condensates from reference cigarettes and different modified cigarettes has been investigated on the mouse skin. The following results have been obtained: 1. Reconstituted tobacco sheets made from the blend of the reference cigarette T as well as different other tobacco mixtures showed a reduced tumorigenic effect. 50% or 20% of reconstituted tobacco sheets as additive to the tobacco T showed reduced tumorigenic effect too. 2. A dark tobacco mixture (cigar type) as well as the Virginia tobacco of the mixture T showed no significant differences in biological activity compared to the reference tobacco. Condensate of the Burley tobacco of the blend T showed a reduced tumorigenic effect. 3. A small amount of nitrate as additive (1.8% total nitrate) only showed a limited reduction of the tumorigenic effect. 4. Condensate of a cigarette with commercially used filters, 20% reconstituted tobacco sheets and a total nitrate content of 1.8% showed a distinctly reduced tumorigenic effect. 5. Statistical evaluations of this experiment indicated that each of the applied dose should not be too high. Application of high doses did not lead to a further increase of tumor incidence. Cytotoxicity and viscosity of higher concentrated solutions may be responsible for this fact.

[Experimental studies on the rumorigenic activity of cigarette smoke condensate on mouse skin. VI. Fractionation of cigarette smoke condensate (author's transl)]. / Experimentelle Untersuchungen über die tumorerzeugende Wirkung von Zigarettenrauch-Kondensaten an der Mäusehaut. VI. Mitteilung: Untersuchungen zur Fraktionierung von Zigarettenrauch-Kondensat

This experiment has been performed to clarify the question to which extent fractions containing polycyclic aromatic hydrocarbons (PAH) or other carcinogenic compounds are responsible for the biological activity of cigarette smoke condensate. With chromatographic procedures using organic gels it was possible to separate quantitatively polar compounds from the PAH-fraction and to obtain fraction IX representing 0.4% of the whole condensate. In this fraction the PAH were enriched 250fold. Significant losses of tumorigenic effects by this fractionation method could not be observed. This PAH-containing fraction showed 50% of activity compared with the overall activity of whole smoke condensate of a reference cigarette. A so-called PAH-free fraction showed with 7% of the overall activity of the whole smoke condensate a weak carcinogenic effect. The importance of PAH for the tumorigenic effect of cigarette smoke is emphasized by these results.

Effect of high doses of nicotine in pigs. I. Changes of the electrocardiogram.

Pigs in which venous catheters were positioned for long-term use were injected i.v. with high doses of nicotine in physiol. saline. The LD50 was 2.656 mg/kg body weight. Clinical symptoms were mainly: forced respiration, muscular tremor to tetanoid spasms, cyanosis of the skin, salivation and sometimes vomiting. The degree and duration of symptoms were dose-dependent. Ecg changes in anaesthesized pigs following intravenous nicotine injections of 0.126 mg/kg and 0.378 mg/kg at 15 minutes' interval were immediately commencing disturbances of the heart rate in form of bradycardia and asystolia. After 5 sec we observed extrasystoles, tachycardia, sino-auricular block and AV-block of first and second degree as well as a number of T- and P-changes. Changes of the ecg were observed generally for 10 to 15 min, however, the T-wave remained sometimes negative or biphasic-preterminal negative for some hours.

Uptake of carbon monoxide in blood of miniture pigs and other mammals.

Different affinities of blood for CO were observed in in vivo and in vitro experiments. Hamsters showed the greatest relative affinity (1.0), the corresponding value for rats was 0.8, for pigs 0.74 and for rabbits 0.58. The upward shift of the saturation curves was dependent on the rate of respiratory exchange per unit of body weight, e.g. the curves were less steep for pigs than for rabbits. After increased motor activity the equilibrium saturation of CO in blood is reached more rapidly. From the results of in vitro experiments the following affinity constants for the blood of different species could be calculated: pig K = 130, hamster K = 181, rat I = 141, rabbit K = 109. For equal atmospheric CO concentrations the saturation values were lower (37-40%) in experiments in vitro than in vivo. Similar saturation values were obtained with light excluded, when O2 concentration was decreased to the level of alveolar oxygen concentration. With regard to the affinity of blood for CO, the blood of domestic pigs did not differ from that of minature pigs in in vitro experiments.