title: Hydrogen peroxide via thromboxane A2 receptors mediates myogenic response of small skeletal muscle veins in rats.
abstract: We aimed to test two hypotheses: (1) isolated small veins develop substantial myogenic tone in response to elevation of intraluminal pressure, (2) H2O2 contributes to the mediation of myogenic response via activation of arachidonic acid (AA) cascade and release constrictor prostaglandins.
  
  
  METHODS
  Small veins were isolated from gracilis muscle of male rats, then cannulated. Changes of diameter to increases in intraluminal pressure, H2O2 and arachidonic acid in the presence and absence of various inhibitors were measured by videomicroscope and microangiometer. At the end of experiments the passive diameter were obtained in Ca2+ -free PSS solution.
  
  
  RESULTS
  Isolated rat gracilis muscle small veins developed a substantial myogenic tone in response to increases in intraluminal pressure (1-12 mmHg). Calculated maximum myogenic tone was 70 ± 5% at 10 mmHg. Presence of catalase or indomethacin or SQ 29,548 reduced significantly the pressure-induced myogenic response. Also, H2O2 (10-9-10-5 M) and arachidonic acid (10-7-10-4 M) elicited concentration dependent constrictions, which were inhibited by the presence of indomethacin or SQ 29,548.
  
  
  CONCLUSIONS
  We propose that both myogenic response and pressure-induced release of H2O2 play important roles in regulating the vasomotor function of venules both in physiological and pathological conditions.
authors.affiliation: Department of Plastic Surgery, Military Hospital - State Health Centre, Budapest, Hungary Department of Pathophysiology, Semmelweis University, Budapest, Hungary.
authors.forename: B
authors.initials: B
authors.lastname: Debreczeni
authors.forename: E
authors.initials: E
authors.lastname: Gara
authors.forename: Z
authors.initials: Z
authors.lastname: Veresh
authors.forename: A
authors.initials: A
authors.lastname: Marki
authors.forename: A
authors.initials: A
authors.lastname: Racz
authors.forename: R
authors.initials: R
authors.lastname: Matics
authors.forename: J
authors.initials: J
authors.lastname: Hamar
authors.forename: A
authors.initials: A
authors.lastname: Koller
mesh_terms: D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism*; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply*; D011312:Pressure; D051381:Rats; D017208:Rats, Wistar; D044244:Receptors, Thromboxane A2, Prostaglandin H2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013928:Thromboxane A2 / Q000378:metabolism; D014680:Veins / Q000187:drug effects / Q000378:metabolism
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D044244:Receptors, Thromboxane A2, Prostaglandin H2; D013928:Thromboxane A2; C045749:SQ 29548; D006861:Hydrogen Peroxide; D007213:Indomethacin
keywords: SQ 29,548; Small veins; arachidonic acid; catalase; hydrogen peroxide; indomethacin; myogenic response; prostaglandins