Diazepam effects on frog skin cyclic nucleotide phosphodiesterase.
1. The activities of cAMP phosphodiesterases (cAMP-PDE) have been measured in the homogenate of the skin of Rana esculenta. 2. The tissue possesses two distinct enzymes: a "low" Km PDE (Km = 0.42 x 10(-6) M; Vmax = 16 pmol/mg protein/min) and a "high" Km PDE (Km = 180 x 10(-6) M; Vmax = 2853 pmol/mg prot/min). Only the "high" Km form is stimulated by calcium. 3. Diazepam (1-0.5 mM) significantly inhibits both enzymes, the inhibition being of competitive type.
Margiotta
M
M
Institute of General Physiology, University of Bari, Italy.
Borasio
P G
PG
Ardizzone
C
C
Lippe
C
C
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000502:physiology; D003975:Diazepam / Q000494:pharmacology*; D066298:In Vitro Techniques; D011893:Rana esculenta; D012867:Skin / Q000201:enzymology*
D015105:3',5'-Cyclic-AMP Phosphodiesterases; D003975:Diazepam; D002118:Calcium