Central blockade of (methyl-)atropine on carbachol drinking: A dose-response study

Administration of carbachol in the tractus diagonalis in rats elicited drinking and no eating. Norepinephrine administered in the same place did not induce drinking or eating. The specific drinking response induced by stimulation with 7.2 nmol (= 1.3 μg) of carbachol was gradually inhibited by preceding injections of graded doses of atropine and methylatropine at the same site. A 90% inhibiting action of atropine and methylatropine was possible with a 3–10 times lower dose (0.18 μg) than used in earlier studies. Significant differences between the inhibition by atropine and methylatropine could not be demonstrated. A possible difference in inhibition at the lowest dose of atropine and methylatropine used (= 0.04 μg) was discussed

The role of the tractus diagonalis in drinking behaviour induced by central chemical stimulation, water deprivation and salt injection

The role of the tractus diagonalis in drinking behaviour induced by central chemical stimulation, 23-hr water deprivation and injection of a hypertonic sodium chloride solution was investigated by means of central and peripheral administration of atropine and methylatropine. The effect of the same doses of centrally and peripherally administered anticholinergics was greater on carbachol-induced drinking than on deprivation-induced drinking. Salt-induced drinking was only influenced by peripheral administration of the anticholinergics. The results indicate the presence of a central cholinergic and a peripheral cholinergic active mechanism in carbachol-induced drinking; a central cholinergic, a peripheral cholinergie and a non-cholinergic mechanism in deprivation-induced drinking; and a central cholinergic, a peripheral cholinergic and a non-cholinergic mechanism in salt-induced drinking. It is concluded that a cholinergic system cannot be the system that has an overall control over water intake behaviour. The results obtained make it questionable whether the tractus diagonalis has a specific function in the series of events that lead to water intake after water deprivation or a salt injection

The effects of Haemophilus influenzae vaccination on an aphylactic mediator release and isoprenaline-induced inhibition of mediator release

The influence of Haemophilus influenzae on anaphylactic mediator from ovalbumin-sensitized isolated guinea pig lungs was investigated. Lungs from H. influenzae-vaccinated animals released protaglandins and thromboxanes following a smaller dose of ovalbumin than was effective in non-vaccinated animals. Histamine release was significantly increased in 4 day-vaccinated animals but not 1 or 10 days after vaccination, while broncho-constriction was potentiated in 1 and 4 day-vaccinated animals. This increased histamine release was achieved following 2 μg ovalbumin. In contrast, doses of 10 μg and 1 mg ovalbumin respectively did not affect and decreased histamine release in the vaccinated group. The inhibition of anaphylactic mediator release by an infusion of 6 × 10−9 M isoprenaline was significantly attenuated by H. influenzae vaccination. These results indicate an increased sensitivity to antigenic challenge and suggest that the functioning of β-adrenoceptors was decreased as a result of H. influenzae vaccination

Specific leukotriene formation by purified human eosinophils and neutrophils

Human granulocytes isolated from peripheral blood have been described to synthesize both LTB4 and LTC4 from arachidonic acid. We have observed that the amount of LTC4 produced by human granulocyte preparations is strongly dependent on the relative amount of eosinophils. To investigate a possibly significant difference in leukotriene synthesis of the eosinophilic and neutrophilic granulocytes, we developed a purification method to isolate both cell types from granulocytes obtained from the blood of healthy donors. Leukotrienes were generated by incubation of the purified cells with arachidonic acid, calcium ionophore A23187, calcium-chloride and reduced glutathione. Surprisingly, eosinophils were found to produce almost exclusively the spasmogenic LTC4. In contrast, neutrophils produce almost exclusively the chemotactic LTB4, its omega-hydroxylated metabolite 20-hydroxy-LTB4 and two non-enzymically formed LTB4 isomers