title: Identification, characterization, and functional role of phosphodiesterase type IV in cerebral vessels: effects of selective phosphodiesterase inhibitors.
abstract: The role of the phosphodiesterase type IV isozyme (PDE IV) in the regulation of cerebrovascular tone was investigated in the canine basilar artery in vitro and in vivo. The PDE isozymes extracted from the canine basilar artery were isolated by diethylaminoethanol (DEAE)-Sepharose affinity chromatography and identified based on sensitivity to isozyme-selective PDE inhibitors. [3H]cAMP hydrolysis was observed in one major and one minor peak of activity. The predominant peak was inhibited by the addition of cGMP (25%), siguazodan (26%), rolipram (39%), and the combination of siguazodan and rolipram (95%). Selective PDE IV inhibitors BRL 61063, rolipram, and denbufylline were equieffective inhibitors of [3H]-ccAMP hydrolysis mediated by PDE IV isolated from the canine basilar artery [concentrations producing 50% inhibition (IC50S) = 0.21 +/- 0.05 microM, 0.67 +/- 0.23 microM, and 0.73 +/- 0.16 microM, respectively]. In precontracted isolated ring segments of the canine basilar artery, selective PDE IV inhibitors produced potent and complete relaxation (IC50S < 150 nM). In contrast, zaprinast (a selective PDE V inhibitor) and siguazodan (a selective PDE III inhibitor) produced only weak relaxation of the basilar artery (IC50S = 4.5 microM and > 10 microM, respectively). Vasorelaxation produced by PDE IV inhibitors was not altered by removing the endothelium, 1-NAME, or adenosine receptor antagonism. In a canine model of acute cerebral vasospasm, all three selective PDE IV inhibitors reversed basilar artery spasm produced by autologous blood without altering mean arterial blood pressure. In contrast, prolonged treatment with BRL 61063 failed to alter the development of basilar spasm in the two hemorrhage canine models of chronic cerebral vasospasm. Denbufylline-induced relaxation in vitro was also significantly impaired in basilar arteries obtained from the model of chronic vasospasm. In conclusion, PDE IV appears to be the predominant isozyme regulating vascular tone mediated by cAMP hydrolysis in cerebral vessels. In addition, vasorelaxation modulated by PDE IV is compromised in chronic cerebral vasospasm associated with subarachnoid hemorrhage.
authors.affiliation: Department of Cardiovascular Pharmacology, SmithKline Beecham Pharmaceutics, King of Prussia, Pennsylvania, USA.
authors.forename: R N
authors.initials: RN
authors.lastname: Willette
authors.forename: A O
authors.initials: AO
authors.lastname: Shiloh
authors.forename: C F
authors.initials: CF
authors.lastname: Sauermelch
authors.forename: A
authors.initials: A
authors.lastname: Sulpizio
authors.forename: M P
authors.initials: MP
authors.lastname: Michell
authors.forename: L B
authors.initials: LB
authors.lastname: Cieslinski
authors.forename: T J
authors.initials: TJ
authors.lastname: Torphy
authors.forename: E H
authors.initials: EH
authors.lastname: Ohlstein
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000818:Animals; D001488:Basilar Artery; D002536:Cerebral Arteries / Q000201:enzymology*; D000242:Cyclic AMP / Q000502:physiology; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D004285:Dogs; D004353:Drug Evaluation, Preclinical; D002546:Ischemic Attack, Transient / Q000150:complications / Q000188:drug therapy / Q000201:enzymology; D007527:Isoenzymes / Q000302:isolation & purification / Q000502:physiology*; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D010727:Phosphoric Diester Hydrolases / Q000302:isolation & purification / Q000502:physiology*; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology / Q000633:toxicity; D011760:Pyrrolidinones / Q000494:pharmacology / Q000627:therapeutic use; D020889:Rolipram; D015290:Second Messenger Systems; D013345:Subarachnoid Hemorrhage / Q000201:enzymology / Q000209:etiology / Q000517:prevention & control; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology / Q000633:toxicity; D014662:Vasoconstrictor Agents / Q000494:pharmacology / Q000633:toxicity; D014665:Vasodilator Agents / Q000494:pharmacology / Q000627:therapeutic use; D014970:Xanthines / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D007527:Isoenzymes; D010726:Phosphodiesterase Inhibitors; D011450:Prostaglandin Endoperoxides, Synthetic; D011760:Pyrrolidinones; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D014970:Xanthines; C043898:denbufylline; C086163:8-amino-1,3-bis(cyclopropylmethyl)xanthine; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D020889:Rolipram