| Abstract: | A variant of human growth hormone (hGH), in which 15 amino acids are missing (commonly referred to as 20K-hGH in contrast to the traditional form which is referred to as 22K-hGH), is known to exist in human pituitary glands. However, lack of a method to measure it in blood has hindered investigations of its physiopathology. We have applied a newly-developed technique called GEISAA for its detection in small volumes of human plasma. The method is based upon the lower Mr of the variant and its ability to partially crossreact with existing antibodies for 22K-hGH. It consists of retrieval of the substance from plasma by immunoprecipitation, separation from 22K-hGH by NaDodSO4-polyacrylamide gel electrophoresis, transfer onto nitrocellulose paper by electroblotting and visualization by immunostaining and autoradiography. It revealed the 20K-hGH in plasma of some normal individuals and in that of an acromegalic patient. Furthermore, plasma concentration of the variant rose in conjunction with 22K-hGH following exercise, a natural stimulus for GH release. These results show that the 20K-hGH circulates under normal conditions and it is measurable by GEISAA using existing antibodies. |
