ATPases of the cat carotid body and of the neighbouring ganglia.

The average ATPase activity in homogenates of the cat carotid body is found to be 20 nmol Pi liberated per minute per mg fresh tissue weight at 25 degrees C. ATPase activity in the nodose ganglion and the superior cervical ganglion is found in the same range. Most of the activity remains in the supernatant after removal of the mitochondria by centrifugation. The activity is inhibited by ouabain only marginally (ganglia) or not at all (carotid body). In all these organs up to 80% of the activity is seen in the absence of Mg2+ and the presence of increasing concentrations of Ca2+.