title: Expression of adenylate cyclase subtypes II and IV in the human outflow pathway.
abstract: OBJECTIVE
  It has been demonstrated that low doses of pilocarpine and other muscarinics substantially increase outflow facility in the isolated human outflow system devoid of ciliary muscle. These cholinergic-induced facility responses were thought possibly to be due to elevation of cAMP as a result of the presence of adenylate cyclases II (AC-II) and IV (AC-IV). Therefore, whether these isoforms are present in outflow tissues was examined.
  
  
  METHODS
  Human anterior segments were perfused with carbachol (10(-9)-10(-5) M), and outflow facility and cAMP levels in the perfusate were measured simultaneously. Isolated trabecular meshwork (TM) were incubated with carbachol (10(-7) M), and the subsequent changes in cAMP were measured by radioimmunoassay. AC-II and AC-IV were characterized in ocular tissue with reverse transcription-polymerase chain reaction and in situ hybridization.
  
  
  RESULTS
  Outflow facility increased, in a dose-dependent manner, by 10%, 16%, and 27% in response to 10(-9), 10(-7), and 10(-5) M carbachol, respectively. Similarly, cAMP increased by 9%, 70%, and 210% in response to 10(-9), 10(-7), and 10(-5) M carbachol, respectively. In addition, cAMP levels significantly increased by 39% in isolated TM strips incubated with 10(-7) M carbachol. AC-II was detected in most normal tissue examined, but not in any cultured cell lines or any glaucomatous tissue. AC-IV was also widely expressed in most normal tissues, faintly detected in some glaucoma tissue, but not detected in most cultured cells.
  
  
  CONCLUSIONS
  The presence of AC-II and AC-IV in outflow tissues supports the hypothesis that cholinergics may indeed exert an effect on outflow facility, mediated by cAMP, which is independent of muscle contraction.
authors.affiliation: Boston University School of Medicine, Department of Ophthalmology, Massachusetts 02118, USA.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: N
authors.initials: N
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Schroeder
authors.forename: K A
authors.initials: KA
authors.lastname: Erickson
mesh_terms: D000262:Adenylyl Cyclases / Q000096:biosynthesis / Q000235:genetics*; D000368:Aged; D000369:Aged, 80 and over; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D018679:Cholinergic Agonists / Q000494:pharmacology; D002924:Ciliary Body / Q000187:drug effects / Q000201:enzymology*; D003315:Cornea / Q000187:drug effects / Q000201:enzymology; D000242:Cyclic AMP / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D015870:Gene Expression; D005901:Glaucoma / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D017403:In Situ Hybridization; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012590:Sclera / Q000187:drug effects / Q000201:enzymology; D014129:Trabecular Meshwork / Q000187:drug effects / Q000201:enzymology*
chemical_list: D018679:Cholinergic Agonists; D017931:DNA Primers; D012333:RNA, Messenger; D002217:Carbachol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; C100622:adenylyl cyclase 2; C406262:adenylyl cyclase 4