Abstract
The addition in vitro of insulin to rat adipose tissue (epididymal) produces marked metabolic changes which may be followed by measurement of the net gas exchange of the tissue. Using this method to monitor the metabolic action of insulin, concomitant observations with the electron microscope on the tissue have been made. These reveal that pronounced morphological changes are induced by insulin. The plasma membranes of the adipose cells become invaginated at many sites to form minute finger-like indentations. Numerous tiny, membrane-bounded vesicles are also present and arranged in relationship to the plasma membrane in such a way as to suggest that their formation occurred when a recessed fold was pinched off. Deeper in the cytoplasm, especially in specimens that had been incubated a longer time, numerous large, smooth, membrane-limited vesicles are seen. Finally, in these incubated specimens the cytoplasmic matrix has lost much of its granular nature, small lipid droplets are frequently found in the cytoplasm and suggestive changes have occurred in mitochondria. In control specimens, incubated without insulin for identical periods of time, indentations and vesicles in the plasma membrane are sparse at best and no vesicles or membrane-bound spaces appear deeper in the cytoplasm. The metabolic and morphologic changes induced by insulin seem to be interdependent events. Both changes appear to be initiated rapidly and concomitantly in the tissue. Both processes are initiated by insulin at concentrations considered to be physiological, 0.004 µg. (100 µunits) per ml. Insulin treated with alkali fails to initiate either process. It is concluded that insulin initiates pinocytosis in rat adipose tissue and the possible significance of this process in the mode of action of insulin is discussed.
Full Text
The Full Text of this article is available as a PDF (1.7 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- BALL E. G., MARTIN D. B., COOPER O. Studies on the metabolism of adipose tissue. I. The effect of insulin on glucose utilization as measured by the manometric determination of carbon dioxide output. J Biol Chem. 1959 Apr;234(4):774–780. [PubMed] [Google Scholar]
- BUCK R. C. The fine structure of endothelium of large arteries. J Biophys Biochem Cytol. 1958 Mar 25;4(2):187–190. doi: 10.1083/jcb.4.2.187. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DALTON A. J., FELIX M. D. A comparison of mesothelial cells and macrophages in mice after the intraperitoneal inoculation of melanin granules. J Biophys Biochem Cytol. 1956 Jul 25;2(4 Suppl):109–114. doi: 10.1083/jcb.2.4.109. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HAGEN J. M., BALL E. G., COOPER O. Studies on the metabolism of adipose tissue. II. The effect of changes in the ionic composition of the medium upon the response to insulin. J Biol Chem. 1959 Apr;234(4):781–786. [PubMed] [Google Scholar]
- HARFORD C. G., HAMLIN A., PARKER E. Electron microscopy of HeLa cells after the ingestion of colloidal gold. J Biophys Biochem Cytol. 1957 Sep 25;3(5):749–756. doi: 10.1083/jcb.3.5.749. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LEVINE R., GOLDSTEIN M. S., HUDDLESTUN B., KLEIN S. P. Action of insulin on the 'permeability' of cells to free hexoses, as studied by its effect on the distribution of galactose. Am J Physiol. 1950 Oct;163(1):70–76. doi: 10.1152/ajplegacy.1950.163.1.70. [DOI] [PubMed] [Google Scholar]
- MANCHESTER K. L., YOUNG F. G. Location 14C in protein from isolated rat diaphragm incubated in vitro with [14C] amino acids and with 14C02. Biochem J. 1959 May;72(1):136–141. doi: 10.1042/bj0720136. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MANCHESTER K. L., YOUNG F. G. The effect of insulin on incorporation of amino acids into protein of normal rat diaphragm in vitro. Biochem J. 1958 Nov;70(3):353–358. doi: 10.1042/bj0700353. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MOORE D. H., RUSKA H. The fine structure of capillaries and small arteries. J Biophys Biochem Cytol. 1957 May 25;3(3):457–462. doi: 10.1083/jcb.3.3.457. [DOI] [PMC free article] [PubMed] [Google Scholar]
- National Academy of Sciences: Abstracts of Papers Presented at the 96th Annual Meeting, 27-29 April 1959, Washington, D.C. Science. 1959 May 8;129(3358):1282–1290. doi: 10.1126/science.129.3358.1282. [DOI] [PubMed] [Google Scholar]
- ODOR D. L. Uptake and transfer of particulate matter from the peritoneal cavity of the rat. J Biophys Biochem Cytol. 1956 Jul 25;2(4 Suppl):105–108. doi: 10.1083/jcb.2.4.105. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PALAY S. L., KARLIN L. J. An electron microscopic study of the intestinal villus. II. The pathway of fat absorption. J Biophys Biochem Cytol. 1959 May 25;5(3):373–384. doi: 10.1083/jcb.5.3.373. [DOI] [PMC free article] [PubMed] [Google Scholar]
- ROSE G. G. Microkinetospheres and VP satellites of pinocytic cells observed in tissue cultures of Gey's strain HeLa with phase contrast cinematographic techniques. J Biophys Biochem Cytol. 1957 Sep 25;3(5):697–704. doi: 10.1083/jcb.3.5.697. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WINEGRAD A. I., RENOLD A. E. Studies on rat adipose tissue in vitro. I. Effects of insulin on the metabolism of glucose, pyruvate, and acetate. J Biol Chem. 1958 Aug;233(2):267–272. [PubMed] [Google Scholar]
- WINEGRAD A. I., RENOLD A. E. Studies on rat adipose tissue in vitro. II. Effects of insulin on the metabolism of specifically labeled glucose. J Biol Chem. 1958 Aug;233(2):273–276. [PubMed] [Google Scholar]
- WOOL I. G., KRAHL M. E. Incorporation of C14-amino acids into protein of isolated diaphragms: an effect of insulin independent of glucose entry. Am J Physiol. 1959 May;196(5):961–964. doi: 10.1152/ajplegacy.1959.196.5.961. [DOI] [PubMed] [Google Scholar]
- WOOL I. G., KRAHL M. E. Incorporation of C14-histidine into protein of isolated diaphragms: interaction of fasting, glucose and insulin. Am J Physiol. 1959 Aug;197:367–369. doi: 10.1152/ajplegacy.1959.197.2.367. [DOI] [PubMed] [Google Scholar]
