The facilitative actions of bay K 8644 on norepinephrine and KCL-induced contractures of rabbit aortic rings

Michael T. Piascik, Michael Babich

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The effect of the calcium channel agonist BAY K 8644 on the ability of KCl and norepinephrine to induce contractions of rabbit aortic rings has been examined in Krebs-Henseleit buffer containing either 4.0 or 6.8 mM potassium. BAY K 8644 (10-8 to 10-6 M) alone induced slowly developing aortic contractures which were 10 (at 4.0 mM potassium) or 20 (at 6.8 mM potassium) percent of the maximum obtainable with norepinephrine. These contractions were not observed in every experiment, but were more likely to occur at 6.8 mM (71% at 10-6 M BAY K 8644) when compared to 4.0 mM (31% at 10-6 M BAY K 8644) potassium buffer. BAY K 8644, in either potassium buffer, induced a statistically significant shift to the left in the norepinephrine dose-response curve. The norepinephrine dose-response curve was significantly curvilinear in the presence of 3 × 10-8 M BAY K 8644 (6.8 mM potassium) and 10-6 M BAY K 8644 (4.0 mM potassium). Similarly, BAY K 8644 induced sinistral shifts in the KCl dose-response curve with a curvilinear function observed at 3 × 10-7 M BAY K 8644. These data show that BAY K 8644 is capable of inducing aortic contractures at potassium concentrations significantly lower than previously reported. Furthermore, BAY K 8644 facilitates opening of calcium channels by either potassium or norepinephrine. In contrast to others, our data indicates that BAY K 8644 can effect calcium channels activated by norepinephrine. Finally, our data suggest that the alpha and dihydropyridine receptors are capable of interacting and that occupation of one receptor can affect the action of a compound binding to the other receptor.

Original languageEnglish (US)
Pages (from-to)725-734
Number of pages10
JournalLife Sciences
Volume38
Issue number8
DOIs
StatePublished - Feb 24 1986
Externally publishedYes

Fingerprint

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
Contracture
Norepinephrine
Potassium
Rabbits
Calcium Channels
Buffers
Calcium Channel Agonists
L-Type Calcium Channels
Occupations

ASJC Scopus subject areas

  • Pharmacology

Cite this

The facilitative actions of bay K 8644 on norepinephrine and KCL-induced contractures of rabbit aortic rings. / Piascik, Michael T.; Babich, Michael.

In: Life Sciences, Vol. 38, No. 8, 24.02.1986, p. 725-734.

Research output: Contribution to journalArticle

Piascik, Michael T. ; Babich, Michael. / The facilitative actions of bay K 8644 on norepinephrine and KCL-induced contractures of rabbit aortic rings. In: Life Sciences. 1986 ; Vol. 38, No. 8. pp. 725-734.
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