Prasad K
Cardiovasc Res. 1975 May;9(3):355-65. doi: 10.1093/cvr/9.3.355.
The effects of glucagon in concentrations of 0.294 times 10(-6) mol/l, 1.47 times 10(-6) mol/l; 2.94 times 10(-6) mol/l, 5.8 times 10(-6) mol/l, and 1.47 times 10(-5) mol/l on the simultaneously recorded action potentials and contractions; and microsomal and sarcolemmal Na+-tk+-atpase in the myocardium of the guinea pig, rabbit, dog, and pig were investigated. Glucagon in all the concentrations produced an inhibition of the Na+-K+-ATPase associated with an increase in the contractility and shortening of the duration of action potential in dog myocardium. The increase in contraction was concentration-dependent up to a certain concentration. Inhibition of sarcolemmal ATPase was more than that of microsomal ATPase. In none of the concentrations did glucagon produce any significant changes in the Na+-K+-ATPase. In none of the concentrations did glucagon produce any significant changes in the Na+-K+-ATPase, contractility, and action potential duration in the myocardium of guinea pig, rabbit, or pig. These results suggest that glucagon-induced positive inotropic effect might be due to an increase in the Ca++ influx as a result of inhibition of membrane Na+-K+-ATPase. Shortening of the action potential duration might also be due to an increased efflux of potassium as a result of an inhibition of Na+-K+-ATPase.
研究了浓度为0.294×10⁻⁶mol/l、1.47×10⁻⁶mol/l、2.94×10⁻⁶mol/l、5.8×10⁻⁶mol/l和1.47×10⁻⁵mol/l的胰高血糖素对豚鼠、兔、狗和猪心肌中同时记录的动作电位和收缩；以及微粒体和肌膜Na⁺-K⁺-ATP酶的影响。所有浓度的胰高血糖素均抑制狗心肌中的Na⁺-K⁺-ATP酶，同时伴有收缩力增加和动作电位时程缩短。收缩的增加在一定浓度范围内呈浓度依赖性。肌膜ATP酶的抑制作用大于微粒体ATP酶。在任何浓度下，胰高血糖素均未使豚鼠、兔或猪心肌中的Na⁺-K⁺-ATP酶、收缩力和动作电位时程发生任何显著变化。这些结果表明，胰高血糖素诱导的正性肌力作用可能是由于膜Na⁺-K⁺-ATP酶受抑制导致Ca²⁺内流增加所致。动作电位时程缩短也可能是由于Na⁺-K⁺-ATP酶受抑制导致钾外流增加所致。
