Role of a pertussis toxin-sensitive protein in the modulation of canine Purkinje fiber automaticity
| Autor: | Peter Danilo, John P. Bilezikian, Susan F. Steinberg, Yung-Kang Chow, M R Rosen |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
Male
medicine.medical_specialty GTP' Physiology Purkinje fibers Stimulation Nicotinamide adenine dinucleotide In Vitro Techniques Pertussis toxin Membrane Potentials Purkinje Fibers chemistry.chemical_compound Hydroxydopamines Phenylephrine Dogs GTP-Binding Proteins Heart Conduction System Heart Rate Internal medicine medicine Animals Virulence Factors Bordetella Oxidopamine Adenosine Diphosphate Ribose biology Dose-Response Relationship Drug Fissipedia Prazosin biology.organism_classification Adenosine diphosphate Endocrinology medicine.anatomical_structure chemistry Pertussis Toxin Female Cardiology and Cardiovascular Medicine medicine.drug |
| Zdroj: | Circulation research. 62(2) |
| ISSN: | 0009-7330 |
| Popis: | We previously have shown that alpha-adrenergic stimulation of canine Purkinje fibers and rat ventricle decreases automaticity. Experiments on rat ventricular myocytes in tissue culture have suggested that the decrease in automaticity induced by alpha-adrenergic stimulation depends on the development of sympathetic innervation and the presence of a pertussis toxin-sensitive, 41-kDa guanosine triphosphate (GTP)-regulatory protein. In the present study, microelectrode and biochemical techniques were used to test the role of the pertussis toxin-sensitive protein and sympathetic innervation in modulating automaticity of adult canine Purkinje fibers. Fibers were incubated in Tyrode's solution alone or in Tyrode's solution plus pertussis toxin (0.1-0.5 microgram/ml) for 24 hours and were then superfused with phenylephrine. Phenylephrine in the 5 x 10(-9)-5 x 10(-8) M range induced a decrease in automaticity in 63% of the 16 fibers not treated with pertussis toxin and an increase in automaticity in 37%. The former group had a higher level of pertussis toxin-sensitive substrate by the [32P]nicotinamide adenine dinucleotide adenosine diphosphate (ADP)-ribosylation assay than the latter. In contrast, all fibers treated with pertussis toxin (0.5 microgram/ml) showed increased automaticity in response to phenylephrine and had no detectable pertussis toxin-sensitive substrate. Over the range of pertussis toxin concentrations studied, there was a smooth concentration-response relation between the substrate levels measured and the automatic response to phenylephrine. As ADP-ribosylatable substrate levels decreased, the percent of fibers showing an increase in automaticity increased.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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