ISSN:
1432-1912
Keywords:
Human atrial preparations
;
α-adrenoceptors
;
Phenylephrine
;
Positive inotropic effect
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary In isolated, electrically driven right auricular strips of the human heart the inotropic effect of phenylephrine was studied. 1. First, the influence of the driving rate on the tension developed (i.e., the frequency-force relationship) was determined by stimulation of the preparations at 0.1, 0.5, 1, 2 and 3 Hz. The force of contraction was lowest at a stimulation rate of 0.1 Hz (36.9 g/g dry weight). The maximally developed force of contraction observed at frequencies of 0.5, 1, and 2 Hz amounted to about 200 g/g dry weight. The values did not significantly differ from each other. 2. The negative log of the EC50(−log EC50) for the positive inotropic effect of phenylephrine determined at a frequency of 0.5 and 1.0 Hz amounted to 5.28±0.08 and 5.34±0.11, respectively. The α-adrenolytic drug phentolamine (3×10−6 M) diminished significantly the −log EC50 to 5.01±0.04 and 4.89±0.10, respectively. 3. At a frequency of 1 Hz a shift of the concentration-response curve to the right was observed after treatment with the β-adrenolytic drug pindolol (3×10−8 M); the −log EC50 of phenylephrine decreased significantly to 4.08±0.07. 4. From these results it is concluded that α-adrenoceptors are present in human atria; they mediate positive inotropic effects and are stimulated by phenylephrine.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00508304
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