Distribution of mast cells in the tracheal tissue components of the guinea pig and its bearing on the Schultz-Dale reaction.

The distribution of mast cells in the tracheal tissue components and its bearing on anaphylaxis was studied in the guinea pig. According to a statistical analysis (Nested ANOVA) the density found in the tissue elements showed the following gradation (mean +/- SE): muscle (299.7 +/- 61.6 cells/mm3) < serosa (802.7 +/- 131.2 cells/mm3) < submucosa (24283.5 +/- 2549.2) < mucosa (48066.4 cells/mm3 +/- 7837.4). Regardless of their location in tissue elements, the cell density in a zone far from the muscle was larger than in a zone close to the muscle. Considering the histamine release capability of mast cells, the density found either in muscle or in its surroundings does not account for the mediation theory unless some postulates ad hoc are introduced. A direct biophysical mechanism is possibly involved. Another alternative is a reflex to histamine, since there is preponderant location of mast cells in mucosa and submucosa.

Modulated intra-train spike responses in the cat superior cervical ganglion in vivo.

The known two-stage facilitation/depression pattern of postganglionic responses was found at high (24 Hz) frequency stimulation of the preganglionic nerves. We found that the depression stage was exaggerated under partial hexamethonium blockade but it was not affected by partial transection of the preganglionic trunk. At low frequency (8 Hz) normal recruitment turned into the familiar two-stage pattern under moderated hexamethonium doses. The depression course under the competitive nicotinic antagonist dihydro-beta-erythroidine was markedly slower than under hexamethonium. These observations are accountable to the known use-dependence effect of hexamethonium.