{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,15]],"date-time":"2026-04-15T15:08:23Z","timestamp":1776265703663,"version":"3.50.1"},"reference-count":56,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T00:00:00Z","timestamp":1774483200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T00:00:00Z","timestamp":1774483200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/501100001537","name":"University of Auckland","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100001537","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001505","name":"Health Research Council of New Zealand","doi-asserted-by":"publisher","award":["22\/559"],"award-info":[{"award-number":["22\/559"]}],"id":[{"id":"10.13039\/501100001505","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["physoc.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["The Journal of Physiology"],"published-print":{"date-parts":[[2026,4]]},"abstract":"\n Abstract<\/jats:title>\n \n Brain injury in preterm infants is common but often difficult to detect in the early stages. The present study investigated whether evolving preterm brain injury after exposure to hypoxia\u2010ischaemia (HI) is associated with dynamic changes in arterial blood pressure variability (BPV) and tested the hypothesis that it was mediated by alpha\u2010adrenoreceptor activity. Chronically instrumented 0.7\u00a0gestation fetal sheep received sham\u2010HI (\n n<\/jats:italic>\n \u00a0=\u00a08) or HI induced by 25\u00a0min of umbilical cord occlusion, followed by\n i.v.<\/jats:sc>\n infusion of either the alpha\u2010adrenergic blocker phentolamine (\n n<\/jats:italic>\n \u00a0=\u00a06) or saline (\n n<\/jats:italic>\n \u00a0=\u00a08) from 15\u00a0min to 8\u00a0h post\u2010HI. HI was associated with acutely reduced beat\u2010to\u2010beat dispersion, sequential and spectral BPV measures, which normalised by 3\u00a0h post\u2010HI, followed by increased low\u2010frequency BPV from 3\u00a0h to 4\u00a0h. From 8\u00a0h to 13\u00a0h post\u2010HI, there was sustained reduction in all BPV measures throughout the secondary phase of injury. Alpha\u2010adrenoreceptor blockade abolished the increase in low\u2010frequency power during the latent phase and partly influenced secondary phase BPV. The HI group also showed greater 3\u00a0hourly reading\u2010to\u2010reading BPV during the first 24\u00a0h post\u2010HI, which was completely suppressed with alpha\u2010adrenoreceptor inhibition. Based on these initial findings, in a subsequent validation cohort [sham\u2010HI (\n n<\/jats:italic>\n \u00a0=\u00a010) and HI\u2010saline (\n n<\/jats:italic>\n \u00a0=\u00a010)] a short\u2010term BPV threshold had 90% sensitivity and 80% specificity for HI. This study highlights the evolving, phase\u2010dependent changes in BPV after HI, that they are partly mediated by alpha\u2010adrenoreceptor activation, and suggests that BPV could be a potential early biomarker for brain injury.\n \n \n image<\/jats:alt-text>\n <\/jats:graphic>\n <\/jats:boxed-text>\n <\/jats:p>\n <\/jats:sec>\n \n Key points<\/jats:title>\n \n \n \n Brain injury in preterm infants is common but often difficult to detect clinically, partly because of their normal low muscle tone and that seizures are typically electrographic.<\/jats:p>\n <\/jats:list-item>\n \n Blood pressure variation (BPV) is mediated mainly by autonomic activity, and so may be a marker for neural injury.<\/jats:p>\n <\/jats:list-item>\n \n In preterm fetal sheep, hypoxia\u2010ischaemia was associated with evolving, phase\u2010dependent changes in BPV.<\/jats:p>\n <\/jats:list-item>\n \n Changes in BPV were partly mediated by alpha\u2010adrenoreceptor activation.<\/jats:p>\n <\/jats:list-item>\n \n These findings support the concept that BPV could be a useful, pragmatic tool to help screen for brain injury.<\/jats:p>\n <\/jats:list-item>\n <\/jats:list>\n <\/jats:p>\n <\/jats:sec>","DOI":"10.1113\/jp290169","type":"journal-article","created":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T13:36:51Z","timestamp":1774532211000},"page":"3457-3475","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Alpha\u2010adrenergic mediated changes in blood pressure variability after hypoxia\u2010ischaemia in preterm fetal sheep"],"prefix":"10.1113","volume":"604","author":[{"given":"Simerdeep K.","family":"Dhillon","sequence":"first","affiliation":[{"name":"Department of Physiology The University of Auckland Auckland New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-5333-1281","authenticated-orcid":false,"given":"Michael 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