title: An Mn2+-stimulated neutral-sphingomyelinase in seminiferous tubules of immature Wistar rats.
abstract: Mammalian sphingomyelinases have been implicated in many important physiological and pathophysiological processes. The seminiferous tubules of immature (19 day-old) Wistar rats have at least three types of sphingomyelinases, a lysosomal one and two microsomal ones. One of the microsomal sphingomyelinases is active at pH 6.5 and is stimulated by Mn2+ > Co2+ > Mg2+, and the other is active at pH 7.4 and is stimulated by Mn2+ > Mg2+ and inhibited by Co2+. The two microsomal enzymes are only slightly inhibited by EDTA and at pH 7.4 the stimulatory effects of Mn2+ and Mg2+ are additive. These data characterize the existence of two different membrane-bound sphingomyelinases in the seminiferous tubules of the rat.
authors.affiliation: Departamento de Bioquímica, ICBS, UFRGS, Porto Alegre, RS, Brazil.
authors.forename: P E
authors.initials: PE
authors.lastname: Raimann
authors.forename: I C
authors.initials: IC
authors.lastname: Custodio de Souza
authors.forename: E A
authors.initials: EA
authors.lastname: Bernard
authors.forename: F C
authors.initials: FC
authors.lastname: Guma
mesh_terms: D000367:Age Factors; D000818:Animals; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D008670:Metals / Q000494:pharmacology; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D012671:Seminiferous Tubules / Q000187:drug effects / Q000201:enzymology*; D013108:Sphingomyelin Phosphodiesterase / Q000187:drug effects* / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism
chemical_list: D008670:Metals; D013109:Sphingomyelins; D008345:Manganese; D013108:Sphingomyelin Phosphodiesterase; D008274:Magnesium