{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T09:35:22Z","timestamp":1776850522600,"version":"3.51.2"},"reference-count":0,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2017,8,11]],"date-time":"2017-08-11T00:00:00Z","timestamp":1502409600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2017,8,11]],"date-time":"2017-08-11T00:00:00Z","timestamp":1502409600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Dev Pharmacol Ther"],"abstract":"<jats:p>The opioid antagonists, naloxone (NOX) and naltrexone (NTX), were found to\nproduce dose-dependent increases in fetal mean arterial pressure over a dose range of 5-\n80 mg\/kg. There was a concomitant decrease in fetal heart rate up to 40 mg\/kg. Above this\ndose, NOX and NTX caused an increase in heart rate as well as blood pressure. NTX produced\nsimilar effects in maternal ewes, although at lower doses (mg\/kg) than those needed for\nfetal lambs. There were no age-related differences in antagonist effects in two fetal age groups\nstudied (100-116 and 124-144 days of gestation). The partial antagonist, levallorphan\n(LVL), produced effects which were qualitatively similar to those produced by NOX and\nNTX in doses up to 20 mg\/kg. These effects were not stereospecific, as the enantiomer of\nLVL, dextrallorphan, produced similar effects at equal doses. Pretreatment with the ar\nadrenoreceptor antagonist, prazosin, abolished the opioid antagonist effects on fetal blood\npressure. We postulate that high doses of opioid antagonists activate sympathetic systems to\nincrease fetal blood pressure through mechanisms which do not involve interactions with \u03bc,\n\u03b4 or \u03ba opioid receptors.<\/jats:p>","DOI":"10.1159\/000457578","type":"journal-article","created":{"date-parts":[[2017,8,11]],"date-time":"2017-08-11T17:08:28Z","timestamp":1502471308000},"page":"28-37","source":"Crossref","is-referenced-by-count":4,"title":["Comparison of High-Dose Opioid Antagonist Effects on Ovine\nFetal Cardiovascular Function"],"prefix":"10.1159","author":[{"given":"C.E.","family":"Dunlap","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"N.K.","family":"Valego","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J.C.","family":"Rose","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2017,8,11]]},"container-title":["Developmental Pharmacology and Therapeutics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000457578","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T08:34:59Z","timestamp":1776846899000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000457578"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,8,11]]},"references-count":0,"URL":"https:\/\/doi.org\/10.1159\/000457578","archive":["Portico"],"relation":{},"ISSN":["0379-8305","2504-2505"],"issn-type":[{"value":"0379-8305","type":"print"},{"value":"2504-2505","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,8,11]]}}}