{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T20:32:22Z","timestamp":1777926742459,"version":"3.51.4"},"reference-count":0,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2009,9,24]],"date-time":"2009-09-24T00:00:00Z","timestamp":1253750400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2009,9,24]],"date-time":"2009-09-24T00:00:00Z","timestamp":1253750400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biol Neonate"],"abstract":"<jats:p>Endogenous opiates have been shown to alter cardiopulmonary activity in a variety of animal models. The present investigation in fetal sheep evaluated the response of heart rate, blood pressure and breathing movements (FBM) to central nervous and intravenous meth-enkephalin and \u03b2-endorphin. Marked bradycardia was noted within 3\u20135 s of intravenous meth-enkephalin administration and lasted less than 10\u201315 s. An 84.8 \u00b1 19.0% prolongation in cardiac cycle length was observed after 20 nmol\/kg meth-enkephalin (p &lt; 0.02). In contrast, there was no significant change in heart rate following 2\u201350 nmol\/kg \u03b2-endorphin. The meth-enkephalin-induced slowing of heart rate was virtually eliminated by autonomic blockade with atropine or hexamethonium but merely partially blunted by naloxone. FBM were not altered by intravenous administration of either opiate. However, both meth-enkephalin and \u03b2-endorphin produced a dramatic increase in FBM following injection into the cisterna magna. Prior to opioid administration, FBM were noted 11 \u00b1 1.4% of the time. Intracisternal opiates resulted in a 43.9 \u00b1 10.1% incidence of FBM for up to 60 min. Parasympathetic blockade with atropine had no effect on the pattern of FBM following intracisternal opiate administration whereas naloxone terminated the increased respiratory activity within 1 min. These data suggest a potential role for endogenous opiates in the modulation of fetal cardiorespiratory function.<\/jats:p>","DOI":"10.1159\/000242610","type":"journal-article","created":{"date-parts":[[2009,9,28]],"date-time":"2009-09-28T08:24:24Z","timestamp":1254126264000},"page":"278-287","source":"Crossref","is-referenced-by-count":5,"title":["Fetal Cardiovascular and Breathing Movement Responses to Endogenous Opiates"],"prefix":"10.1159","author":[{"given":"Alan B.","family":"Lewis","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David A.","family":"Ferry","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mahvash","family":"Sadeghi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2009,9,24]]},"container-title":["Biology of the Neonate"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.karger.com\/Article\/Pdf\/242610","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000242610","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T22:20:13Z","timestamp":1777674013000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000242610"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2009,9,24]]},"references-count":0,"URL":"https:\/\/doi.org\/10.1159\/000242610","archive":["Portico"],"relation":{},"ISSN":["0006-3126","1421-9727"],"issn-type":[{"value":"0006-3126","type":"print"},{"value":"1421-9727","type":"electronic"}],"subject":[],"published":{"date-parts":[[2009,9,24]]}}}