Die Temperaturempfindlichkeit isolierter Lorenzinischer Ampullen

Abstract

The ampullae ofLorenzini of elasmobranchs have a high sensitivity to temperature, as has been found bySand (1938) andHensel (1955) in single fibre preparations. Rapid cooling results in a steep, although temporary increase in impulse frequency; rapid warming is followed by a short and temporary inhibition of discharges. This behaviour very closely resembles that of the “cold” receptors of warm blooded animals. During experiments with isolated ampullae ofLorenzini of the infra- and supraorbital group ofScyllium canicula, we found in two animals some ampullae with an opposite response to temperature changes: rapid cooling inhibited the discharges of the ampullae, while rapid changes to warmth initiated a temporary increase in impulse rate. In some of the ampullae a kind of “adaptation” after fast temperature changes was observed which was also different from what has been described by other authors. The high dynamic response after rapid cooling was followed by a strong diminution in discharge rate. Only after several minutes the impulse frequency again rose to a new and constant level. With rapid warming the behaviour of the spike rate was the mirror image: initially, the frequency dropped to low values but then rose again to a level which was higher than before warming. After this maximum the discharge role fell to a constant frequency. From the results it may be concluded that the localization of the ampullae might be of importance for the “specific” function of the receptor as well as for the differentiation of the peripheral stimulus patterns.

Zusammenfassung

• 1. Es gibt in den Lorenzinischen Ampullen Rezeptoren, die sich bei raschen Temperaturänderungen wie Warmrezeptoren verhalten.

• 2. Eine Reihe von Lorenzinischen Ampullen zeigt nach Temperatursprüngen ein diskontinuierliches Adaptationsverhalten, das der Reaktion bei anderen Reizformen an isolierten Ampullen der infraorbitalen Gruppe sehr ähnlich ist.

• 3. Die Befunde legen den Schluß nahe, daß die Lokalisation der Ampullen sowohl für „spezifische“ Rezeptorleistungen als auch für die Differenzierung des peripheren Reizmusters von Bedeutung ist.