EFFECTS OF NORADRENALINE AND ISOPRENALINE ON THE ELECTRICAL AND MECHANICAL ACTIVITIES OF GUINEA PIG DEPOLARIZED TAENIA COLI

作者：Tetsuo MAGARIBUCHI, Hiroshi Kuriyama · 发表于：The Japanese Journal of Physiology · 年份：1972 · DOI：10.2170/jjphysiol.22.253 · 被引用次数：21 · 研究领域：Ion channel regulation and function、Analytical Chemistry and Sensors、Nitric Oxide and Endothelin Effects

The effects of noradrenaline and isoprenaline on the electrical and mechanical properties of depolarized smooth muscle of the guinea pig taenia coli were investigated by the double sucrose gap method.1. Noradrenaline (10-7-10-5g/ml) decreased the membrane resistance at any given concentration of excess K ion. When increased K ion concentration accelerated the spike discharges, noradrenaline blocked the spike generation as a result of the consequent reduction in membrane resistance, thus causing relaxation. When the excess K ion depolarized the muscle and no spike generation was observed due to depolarization block, noradrenaline no longer caused relaxation of the tissue. Phentolamine (10-5g/ml) completely blocked the effect of noradrenaline.2. Acetylcholine (10-5g/ml) and noradrenaline (10-5g/ml) reduced the membrane resistance and blocked the spike generation to the same extent in 59 mm K-Krebs solution. However, acetylcholine enhanced and noradrenaline reduced the contraction.3. Isoprenaline (10-7-10-5g/ml) reduced the tonic response of the contraction without any marked changes in the membrane resistance, membrane potential and membrane activity, at any given concentration of excess K ion.4. Isoprenaline (10-7-10-5g/ml) did not reduce the tonic response evoked by excess K ion in Na-free solution. It is suggested that external Na ion might be important for the reduction of the internal free Ca ion concentration. In the Cl-deficient (C6H5S0O3), excess K+ condition, isoprenal...