Higgins D, Pappano A J
Circ Res. 1981 Feb;48(2):245-53. doi: 10.1161/01.res.48.2.245.
As early as the 4th embryonic day, the ventricle of the chick embryo responded to isoproterenol (Iso) with an increase in the force of contraction; at all ages studied, this positive inotropic effect was accompanied by an increased rate of tension development. There was a transient, 10-fold decrease in the sensitivity (increase in ED50) of the right ventricle to Iso between the 16th and 21st embryonic day. This change in the sensitivity to Iso was not due either to an increased inactivation of Iso by non-neuronal cells or to a change in the thickness of the ventricle. It was found that adrenergic nerves were first capable of altering ventricular contractility on the 16th embryonic day. Whereas they interfered with the function of adrenergic nerves, injections of reserpine or 6-hydroxydopamine had no effect on the subsensitivity to Iso. Furthermore, these agents did not affect the normal developmental changes in heart weight. We conclude that the local release of transmitter from adrenergic nerves does not cause the transient subsensitivity of the ventricle of the chick embryo to beta-adrenergic agonists.
早在胚胎第4天，鸡胚心室对异丙肾上腺素（Iso）产生反应，收缩力增强；在所有研究的年龄段，这种正性肌力作用都伴随着张力发展速率的增加。在胚胎第16天至21天期间，右心室对Iso的敏感性（ED50增加）出现了短暂的10倍下降。对Iso敏感性的这种变化既不是由于非神经细胞对Iso的失活增加，也不是由于心室厚度的改变。研究发现，肾上腺素能神经在胚胎第16天首次能够改变心室收缩性。虽然注射利血平或6-羟基多巴胺会干扰肾上腺素能神经的功能，但对Iso的低敏感性没有影响。此外，这些药物并不影响心脏重量的正常发育变化。我们得出结论，肾上腺素能神经递质的局部释放不会导致鸡胚心室对β-肾上腺素能激动剂的短暂低敏感性。
