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Single FBMs, occurring at a very low frequency (\u223c8 FBMs\/h), commenced at E16. The incidence of single FBMs increased to \u223c80 FBMs\/h by E20. Episodes of clustered rhythmic FBMs were first observed at E18 (\u223c40 FBMs\/h). The incidence of episodic clustered FBMs increased to \u223c300 FMBs\/h by E20, with the duration of each episode ranging from \u223c40 to 180 s. Doxapram, presumably acting to stimulate carotid body receptors, did not increase FBMs until E20, when the incidence of episodic clustered FBMs increased twofold. Aminophylline, a central-acting stimulant, caused an increase in episodic clustered FBMs after E17, reaching significance at E20 (3-fold increase). Exposing the dam to 10% O<jats:sub>2<\/jats:sub>caused a rapid, marked suppression of FBMs (5-fold decrease) that was readily reversed on exposure to room air.<\/jats:p>","DOI":"10.1152\/jappl.2001.91.1.316","type":"journal-article","created":{"date-parts":[[2017,12,22]],"date-time":"2017-12-22T21:00:46Z","timestamp":1513976446000},"page":"316-320","source":"Crossref","is-referenced-by-count":91,"title":["Ultrasound measurements of fetal breathing movements in the rat"],"prefix":"10.1152","volume":"91","author":[{"given":"Koichi","family":"Kobayashi","sequence":"first","affiliation":[{"name":"Departments of Physiology and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robert P.","family":"Lemke","sequence":"additional","affiliation":[{"name":"Pediatrics, Perinatal Research Centre, University of Alberta, Edmonton, Alberta, Canada T6G 2S2"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John J.","family":"Greer","sequence":"additional","affiliation":[{"name":"Departments of Physiology and"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1096-9861(19970616)382:4<459::AID-CNE3>3.0.CO;2-1"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1096-9861(19970616)382:4<469::AID-CNE4>3.0.CO;2-0"},{"key":"B3","doi-asserted-by":"publisher","DOI":"10.1016\/0034-5687(86)90088-5"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1988.65.6.2420"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1016\/0024-3205(88)90517-6"},{"key":"B6","doi-asserted-by":"publisher","DOI":"10.1016\/0165-3806(95)00170-0"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1999.86.3.779"},{"key":"B8","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.1996.271.5.R1160"},{"key":"B9","doi-asserted-by":"publisher","DOI":"10.1152\/jn.1992.67.4.996"},{"key":"B11","doi-asserted-by":"publisher","DOI":"10.1152\/physrev.1999.79.2.325"},{"key":"B12","doi-asserted-by":"crossref","first-page":"894","DOI":"10.1016\/S0022-3565(25)38357-6","volume":"266","author":"Howell LL.","year":"1993","journal-title":"J Pharmacol Exp Ther"},{"key":"B13","doi-asserted-by":"publisher","DOI":"10.1016\/S0029-7844(96)00344-4"},{"key":"B14","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1991.70.4.1431"},{"key":"B15","doi-asserted-by":"publisher","DOI":"10.1139\/y83-048"},{"key":"B16","doi-asserted-by":"publisher","DOI":"10.1016\/S0095-5108(18)30205-7"},{"key":"B17","first-page":"1","volume":"134","author":"Lakke EA.","year":"1977","journal-title":"The projections to the spinal cord of the rat during development. 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