Effects of nifedipine, BAY K 8644, and pertussis toxin on pressor response to sarafotoxin-b in pithed rats Academic Article uri icon

Overview

MeSH Major

  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
  • Blood Pressure
  • Nifedipine
  • Pertussis Toxin
  • Vasoconstrictor Agents
  • Viper Venoms
  • Virulence Factors, Bordetella

abstract

  • The pressor actions of sarafotoxin-b (SRTX-b) were examined in pithed rats in the presence of the calcium channel antagonist nifedipine or the calcium channel activator BAY K 8644 intraarterially (i.a.) and also after pretreatment with pertussis toxin intravenously (i.v.). SRTX-b produced dose-dependent pressor effects in the pithed rat. The diastolic blood pressure (DBP) recorded in animals treated with the vehicle was 41 +/- 1 mm Hg; administration of BAY K 8644 0.1 or 0.3 mg/kg increased DBP pressure to 50 +/- 1 and 52 +/- 1 mm Hg, respectively, whereas nifedipine 0.1 or 0.3 mg/kg decreased DBP to 39 +/- 1 and 33 +/- 1 mm Hg, respectively. The actions of SRTX-b were significantly inhibited by nifedipine, whereas BAY K 8644 potentiated the pressor actions of SRTX-b. We observed that animals pretreated with pertussis toxin 25 or 50 micrograms/kg 3 days before we conducted the experiments had significantly lower DBP as compared with saline-treated animals. Treatment with pertussis toxin caused the DBP dose-response curve to SRTX-b to be displaced to the right. These results indicate that a nifedipine-sensitive (presumably extracellular) calcium pool is partly responsible for the pressor response induced by SRTX-b. They further suggest that in vascular smooth muscle, at least in some vascular beds, SRTX-b activates a pertussin toxin-sensitive G-protein that is coupled to a receptor-operated calcium or nonspecific cation channel.

publication date

  • January 1990

Research

keywords

  • Academic Article

Identity

Language

  • eng

PubMed ID

  • 1700223

Additional Document Info

start page

  • 495

end page

  • 500

volume

  • 16

number

  • 3