Measurement of Intrauterine Oxygen Tension in the Rat and Its Regulation by Ovarian Steroid Hormones

Abstract

Intrauterine oxygen tension was measured in vivo in the adult virgin rat using an oxygen microelectrode and amplifier assembly coupled with a continuous recording system. Intermittent fluctuations in pO« with varying degrees of regularity were observed. In the uterus of the intact rat the frequency of these alterations and level of average pO> were found to be determined primarily by the patency of the uterine arterioles which supply the capillary network in the endometrium. To only a minor degree did contractile activity of the myometrium affect intrauterine oxygen tension. The topical or intravenous administration of epinephrine hydrochloride or acetylcholine chloride induced vasoconstriction of the arterioles and a decrease in intrauterine pO«. Upon the restoration of blood flow accompanying vasodilation, oxygen tension increased. The topical application of histamine phosphate inci-eased capillary bed engorgement and increased intrauterine pC>2.Following ovariectomy during estrus, average intrauterine oxygen tension increased markedly above estrous levels during the subsequent 5 days. The daily sc injection of estrone (0.5, 1.0 or 5.0 Mg) prevented the post-ovariectomy elevation in average pOs, but had little effect on the rate of pO 2 fluctuation. The administration of progesterone (1.0, 2.0 or 4.0 mg) prevented in part the increase in oxygen tension following ovariectomy, but tended to enhance the rate of fluctuation. The administration of 1.0 /xg estrone and 2.0 mg progesterone together resulted in an average intraluminal pO« level intermediate to and a frequency greater than that obtained with either ovarian steroid alone. It was concluded that the availability of oxygen within the uterus probably is regulated by action of the ovarian steroid hormones on vascular contractility and on metabolic and morphologic changes which affect oxygen availability. {Endocrinology 83: 691, 1968)

Effect of Oxygen Tension on the Amino Acid Utilisation of Human Embryonic Stem Cells

“…A number of studies have demonstrated the advantages of hESC culture at reduced oxygen tensions, including reduced spontaneous differentiation, increased expression of pluripotency markers, fewer chromosomal aberrations and increased rates of proliferation [5,6,7,8,9,35] and low oxygen culture is thought to be more physiological [36,37,38]. …”

The placenta: transcriptional, epigenetic, and physiological integration during development

“…Along these lines, culture in lower O 2 levels helps maintain human ES cells in an undifferentiated state (134). Importantly, the oviducts and uterine horns of mammals exhibit oxygen tension in the 3% range, suggesting that fertilization and the early stages of embryonic development take place in physiologically hypoxic environments (135)(136)(137)(138).…”

HIF1α regulation ofSox9is necessary to maintain differentiation of hypoxic prechondrogenic cells during early skeletogenesis

“…At later stages of development, organ growth that precedes vascular development leads to hypoxic microenvironments (Maltepe and Simon, 1998;Mitchell and Yochim, 1968;Rodesch et al, 1992). During evolution, several organs have adapted to hypoxic developmental conditions and integrated hypoxia into their intrinsic genetic program as an external regulatory signal.…”