Nitroglycerine and catecholamine actions on smooth muscle cells of the canine coronary artery.

Nitroglycerine and catecholamine actions on smooth muscle cells of the canine coronary artery. 1. The membrane potential of smooth muscle cells of the canine coronary artery was ‐ 52 mV, and cells were electrically quiescent. The length and time constant of the membrane were 0.83 mm and 410 msec, respectively. 2. TEA (> 10(‐3) M) depolarized the membrane, increased the membrane resistance and suppressed the rectifying property of the membrane. In 10(‐2) M‐TEA, an outward current pulse evoked a small active response in the canine coronary artery and a large response in the porcine coronary artery. 3. In the canine coronary artery, the minimum [K]o required for contraction was 11.8 mM (‐48 mV), and the maximum amplitude of the contraction was evoked in 89 mM‐[K]o (‐13 mV). The maximum depolarization produced by a tenfold increase in [K]o was 49 mV. 4. In the canine coronary artery, isoprenaline and a low concentration of phenylephrine reduced the resting tension, and a high concentration of phenylephrine (> 5 x 10(‐5) M) produced a contraction without affecting the membrane properties. 5. Nitroglycerine reduced resting tension, suppressed the amplitude and raised the threshold of contraction evoked by excess [K]o, electrical depolarization or phenylephrine. In the canine coronary artery, the minimum concentration of nitroglycerine required to suppress K‐induced contraction (17.7 mM) was 2.8 x 10(‐12) M nitroglycerine. However, resting membrane properties were not affected by 2.8 x 10(‐5) M nitroglycerine. TEA induced electrical response was only a little depressed by 2.8 x 10(‐5) M nitroglycerine in the porcine coronary artery, while the mechanical response was markedly suppressed. 6. In the canine coronary artery, adenosine (> 10(‐5) M) relaxed the tissue in the presence of 17.7 M‐[K]o without affecting the membrane property. ACh (> 5 x 10(‐5) M) had much the same effects as those observed by treatment with adenosine. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Physiology Wiley

Nitroglycerine and catecholamine actions on smooth muscle cells of the canine coronary artery.

The Journal of Physiology, Volume 309 (1) – Jan 1, 1980

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Publisher
Wiley
Copyright
© 2014 The Physiological Society
ISSN
0022-3751
eISSN
1469-7793
DOI
10.1113/jphysiol.1980.sp013502
Publisher site
See Article on Publisher Site

Abstract

1. The membrane potential of smooth muscle cells of the canine coronary artery was ‐ 52 mV, and cells were electrically quiescent. The length and time constant of the membrane were 0.83 mm and 410 msec, respectively. 2. TEA (> 10(‐3) M) depolarized the membrane, increased the membrane resistance and suppressed the rectifying property of the membrane. In 10(‐2) M‐TEA, an outward current pulse evoked a small active response in the canine coronary artery and a large response in the porcine coronary artery. 3. In the canine coronary artery, the minimum [K]o required for contraction was 11.8 mM (‐48 mV), and the maximum amplitude of the contraction was evoked in 89 mM‐[K]o (‐13 mV). The maximum depolarization produced by a tenfold increase in [K]o was 49 mV. 4. In the canine coronary artery, isoprenaline and a low concentration of phenylephrine reduced the resting tension, and a high concentration of phenylephrine (> 5 x 10(‐5) M) produced a contraction without affecting the membrane properties. 5. Nitroglycerine reduced resting tension, suppressed the amplitude and raised the threshold of contraction evoked by excess [K]o, electrical depolarization or phenylephrine. In the canine coronary artery, the minimum concentration of nitroglycerine required to suppress K‐induced contraction (17.7 mM) was 2.8 x 10(‐12) M nitroglycerine. However, resting membrane properties were not affected by 2.8 x 10(‐5) M nitroglycerine. TEA induced electrical response was only a little depressed by 2.8 x 10(‐5) M nitroglycerine in the porcine coronary artery, while the mechanical response was markedly suppressed. 6. In the canine coronary artery, adenosine (> 10(‐5) M) relaxed the tissue in the presence of 17.7 M‐[K]o without affecting the membrane property. ACh (> 5 x 10(‐5) M) had much the same effects as those observed by treatment with adenosine.

Journal

The Journal of PhysiologyWiley

Published: Jan 1, 1980

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