Effects of nifedipine, bay K 8644, and pertussis toxin on pressor response to sarafotoxin-b in pithed rats

Reza Tabrizchi, Christopher R. Triggle

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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 DBF 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 μg/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.

Original languageEnglish
Pages (from-to)495-500
Number of pages6
JournalJournal of Cardiovascular Pharmacology
Issue number3
Publication statusPublished - Sep 1990



  • Calcium channel antagonist and activator
  • Diastolic blood pressure
  • Pertussis toxin
  • Pithed rat
  • Sarafotoxin

ASJC Scopus subject areas

  • Pharmacology
  • Cardiology and Cardiovascular Medicine

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