Effect of Potassium on the Release of [3H]Noradrenaline from Rabbit and Human Pulmonary Artery |
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Authors: | Elek Sylvester Vizi Tamas Torok Kalman Magyar |
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Affiliation: | Institute of Experimental Medicine, Hungarian Academy of Sciences, Semmelweis University of Medicine, Budapest, Hungary;Department of Pharmacodynamics, Semmelweis University of Medicine, Budapest, Hungary |
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Abstract: | The release of [3H]noradrenaline ( [3H]NA) from rabbit and human isolated pulmonary artery has been measured. Removal of external potassium ions enhanced both the resting and stimulated release of [3H]NA from the strips. On adding K+ to tissues which had been suspended in K+-free Krebs solution, the release of [3H]NA was reduced in both stimulated and unstimulated tissues. Selective inhibition of presynaptic alpha 2-adrenoceptors by yohimbine significantly potentiated the release of [3H]NA evoked by stimulation in K+-free solution. The presynaptic inhibitory effect of NA was much less pronounced when the release was enhanced by the removal of external K+. Since the activity of NA, K-ATPase may be affected by removing K+ or by adding it to tissue previously kept in K+-free solution, the results may indicate involvement of the sodium pump in NA release. |
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Keywords: | Rabbit and human pulmonary artery [3H]Noradrenaline release Potassium Negative feedback |
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