Acid and alkaline ceramidases of rat tissues

Abstract

Ceramidase (N-acylsphingosine deacylase) was measured in rat tissue homogenates with N-[1-¹⁴C]oleoyl- and N-[9,10-³H]palmitoyl-sphingosine. Two activities were observed with pH optima of approximately 5 and 8. The activity at pH 8 exceeded that at pH 5 in all tissues and tissue areas examined, and both activities decreased in the following order: kidney > brain stem > cerebrum > cerebellum > liver > spleen > cardiac muscle > lung > psoas muscle. The distribution of activity is not as tissue specific as that of neutral Mg²⁺-stimulated sphingomyelinase which is enriched in cells of neural origin and thus suggests a less specialized role for the alkaline ceramidase.