HAGHIGHI B, TOORI S, SHAJARIAN S. EPINEPHRINE INHIBITS THE A CTIVITY OF PHOSPH ATIDATE PHOSPHOHYDROLASE OF ISOLATED HUMA N HEPATOCYTES. Med J Islam Repub Iran 1999; 13 (2) :139-142
URL:
http://mjiri.iums.ac.ir/article-1-958-en.html
From the Department of Clinical Biochemistry, Isfahan University of Medical Sciences, Isfahan, I.R.Iran
Abstract: (4322 Views)
The effect of epinephrine on phosphatidate phosphohydrolase (PAP) activity of
isolated human hepatocytes was studied. Epineprine inhibited the enzyme activity
progressively at concentrations above 0.1 µM, reaching a maximum inhibition of
64.5% at 100 µM concentration. Inclusion of alprenolol, a β-receptor blocker, in
the incubation mixture abolished the inhibitory effect of epinephrine on PAP,
whereas the (i-receptor antagonist phentolamine, or agonist phenylephrine, did not
significantly change the hormone's effect. Addition of dibutyryl-cAMP or
.aminophylline (a cAMP phosphodiesterase inhibitor) to the incubation mixture
together with epinephrine caused further enzyme inhibiti.on reaching 65.6% and
63.7%, respectively, compared to 49% inhibition caused by epinephrine alone
under the same conditions. Dibutyryl-cAMP alone also inhibited PAP activity
(51 %). The results suggested that epinephrine affects human hepatocyte PAP
activity through β-adrenoceptor activation and cAMP is involved in the mechanism
by which PAP activity is altered.