Potassium Content of Rat Diaphragms Following Hypophysectomy and Incubation with Growth Hormone. ∗

Summary

Experiments were performed to determine if hypophysectomy and growth hormone influence amino acid transport by rat diaphragm through alterations in muscle K⁺ content. Hypophysectomy did not alter in vivo K⁺ content of rat diaphragm. Neither hypophysectomy nor incubation with growth hormone exerted a detectable influence on K⁺ level of the diaphragm in vitro. Moreover, diaphragms which were K⁺ depleted and could not take up K⁺ during the incubation period, still responded to bovine growth hormone with an increase in amino acid transport. Thus it appears unlikely that the effects of hypophysectomy and growth hormone on amino acid transport by rat diaphragm are mediated through changes in muscle K⁺ content.

The authors wish to thank Dr. Frank L. Engel for his interest and critical evaluation of the manuscript.