Oxygen-sensitive chemoreceptors in the branchio-cardiac veins of the crayfish, Astacus leptodactylus.

Oxygen-sensitive activity was recorded from the branchial nerve of the crayfish Astacus leptodactylus in vitro. After the podobranchial and arthrobranchial nerves branch off to the gill, the branchial nerve terminates in the branchio-cardiac vein wall and its surroundings. When the former 2 branches were cut, irregular spontaneous activity could be recorded from a few fiber preparations innervating the branchio-cardiac vein. The branchio-cardiac vein was superfused or perfused with hypoxic or hyperoxic Ringer solution. Impulse frequency increased in response to hypoxia and decreased in hyperoxia. NaCN and almitrine strongly stimulated nerve activity. Baroreceptor activity was also observed. These response characteristics demonstrate that these receptors are Heymans-type chemoreceptors.