Inhibition of camp phosphodiesterase by disodium cromoglycate

Biochemical Pharmacology, Vol. 23, pp 917-920.

Pergamon Press, 1974. Printed in Great Britain

OF CAMPPHOSPHODIESTERASE BY DISQDIM CROMXLY(XE

I~IBITION

ASHIMC. ROY and BRIAN T. WARREN Research Division,

Miles Laboratories

Limited,

Stoke Poges,

Slough SLZ 4LY, England.

Previous

studies’

on the mode of action

shown that the drug blocks a stage

in the allergic

but prior

neither

non-immunological Cyclic

pathway subsequent

triggered

3’,5’-AMP

example,

B-adrenergic

in various

anddibutyryl

been shown to inhibit

heart

;

(Sigma) ;

7

anaphylaxis

cAMPphosphodiesterases

guinea-pig

SRS-A or by DSCGof

of &E-mediated For

cAMPproduction), and prevent

IgE-mediated

34 human ’ , monkey’ and guinea-pig

The enzyme preparations fraction)

as a regulator

.

release

methyl-

cAMP

cfNP (which mimics endogenous CAMPaction)

in rat peritoneal

IASCGto inhibit

The inhibition

activity

the antigen-induced

from hman leucocytes’,

bradykinin,

has also been demonstrated.

(which stimulate

phosphodiesterase

at

combination,

models of immediate hypersensitivity.

stimulants

(which inhibit

degradation)

stimulant.

spasmogen release

(DSCG) have

of spasmogens by acting

to antigen-antibody

(cAMP) has been implicated

reactions

xanthines

release

It does not antagonize

is it a B-adrenergic

allergic

release

the &E-mediated

to spasmogen release.

histamine ;

of disodium cromoglycate

have

of histamine

lung6,

and SRS-A

We have now examined the ability from several

of

sources.

used were human lung homogenate (60%(NH4)2S04

lung homogenate (3,OCOg supernatant

rat peritoneal

cell

preparation

Measurement of CAMPphosphodiesterase on the method of Huang and Kemp8.

(3,ooOg supematant

activity

Samples (1.3ml)

917

fraction);

bovine fraction).

at 37’ for 15 min was based contained

50 & Tris-HCl

PreliminafV communications

9l8

(PH 7.51, 10 mu Mgcl2, 3H-c.4?@(SO,ooO c.p.m.),

0.08 mMunlabelled CAMP,the

enzyme preparation (in 50 mMTris-HC1, pH 7.5 containing 5 mME-mercaptoethanol) with or without drug. water for 3 min.

Reaction was stopped by immersion in boiling

3H-5’~AMP formed from 3H-cAW was converted to 3H-adenosine

by Crotiatua a&ox venom (400 ug/tube), counted.

separated on DEAESephadex A-25 and

None of the drugs examined influence the activity

of the venom

enzyme. ‘The results presented in Table I show that, with one exception, more potent inhibitor theophylline,

than the standard phosphodiesterase inhibitor,

especially

on the preparation from humanlung which is the

probable site of JXCGaction. allergic

IxjCGis a

Of a variety of anti-inflasmmtory and anti-

drugs that were also examined, aspirin,

sodium salicylate,

dexamethasone, mepyramine, phenylbutazone, isoprenaline S salbutamol and phenoxybenzamine, cmly indomethacin ( IDS0 155ti and 253$i for bovine heart and humanlung enzymes, respectively), activity

has been reported’,

degree of specificity Table I.

for which phosphodiesterase inhibitor

showed significant

activiv

indicating

some

for DSCG.

Effect of DSCGand theophylline on CAMP phosphodiesterase activity from different

sources.

Enzymesource

ID5&W DSCG

Theophylline

Humanltmg

380

980

Guinea-pig lung

540

830

Bovine heart

462

470

820

1150

Rat peritoneal The kinetics bovine heart ;

of the inhibition the Dixon”

DSCGwith an inhibitor theophylline,

cells

were investigated with the enzyr~ from

plot (Figure 1) shows competitive inhibition

constant kip 3.0 x 10W4M,comparable to that for

ki 3.3 x 10%.

for

919

Preliminary communicatioas

I

-13

-1.0

Figure 1.

- 0.5

Dixon plot Substrate

Reported results inhibition

0

concentration:

of the effect

inhibiting

results

of isoprenaline

from mast cells

the mast cell

surface.

does not act on this

on the

of SRS-A in rats prepared

the implication

is forthcoming

both passive

The negative

of our

from the work of Taylor et

cutaneous

mast cells

examined the suggestionl‘ by inhibiting

by

through a CAMPdependent mechanism by

of rat peritoneal

One of us had previously

8011M.

They have found that DSCGand isoprenaline

in inhibiting

and the degranulation

release

40$!, -I-

and theophylline

of cAMF7. Evidence supporting

CAMPphosphodiesterases

synergistically

20

in the system examined, DSCGoperates

that,

that DSCGoperates

of this department.

release

-O- ZO$L -A-

by DSCGof the antigen-induced

a mechanism independent

1.0 1.5 DSCG(mM)

for DSCGon bovine heart cAMF’phosphodiesterase.

with IgE antibody would suggest

in vitro

0.5

that DSCGblocks

support

enzyme (A.C. Roy, unpublished).

in the rat

induced by phospholipase-A.

phospholipase-A results

anaphylaxis

act

histamine

lo-~ownto be present

on

the view13 that DSCG

920

Preliminary immunizations

Rece*tly14,

the existenceof phosphodiesterase isoenzymeshas been

suggestedto explaindifferential drug sensitivity.Furtherstudiesto establish the possibleselectiveactionof DSCG on phosphodiesterase isoenzymes from various sources

are underway.

REFERENCES

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212 (1970).

4. E.S.K.Assem and H.O. Schild,Nature,224, 1028 (1969). 5.

T. Ishizaka,K. Ishizaka,R.P. Orange and K.F. Austen,Fed.Proc., 29, 75 (1970).

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(1972).

IO. M. Dixon,Biochem.J., 55, 170 [1953). 11, W.A. Taylor,D. Sheldon,D.H. Francisand I.&i. Roitt,in the press. 12. T.S.C.Orr and J.S.G. Cox, Nature,j?23,197 (1969). 13. M.C. Hines, G.F. Moss and J.S.G. Cox, Biochem.Pharmac., 2,

171 (1972).

14. A.-L. Pichard,J. Hanouneand J.-C, Kaplan,Biochim.Biophys.Acta., 279, 217 (1972).