{
  "id": 9409239,
  "title": "Postnatal Development Shapes the Cardiac Response to Milrinone",
  "url": "https://urgent.news/2026/09/23/postnatal-development-shapes-the-cardiac-response-to-milrinone",
  "topic": "health",
  "section": "Health & Medicine",
  "published": "2026-09-23T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.17.750727v1?rss=1"
  },
  "original_language": "en",
  "account": "Milrinone, a medication that expands the heart's pumping capacity, is commonly used in both children and adults. However, the way the heart responds to milrinone can differ based on how mature the heart is. This study investigated this by examining guinea pig hearts at different ages - neonatal (up to two days old), juvenile (four to ten days old), and adult (six months old).\n\nThe researchers found that as the guinea pig hearts matured, certain measurements such as left ventricular developed pressure, action potential duration, and calcium transient duration all increased. These changes are consistent with the heart's remodeling and improvement in its ability to convert electrical signals into muscle contractions as it matures.\n\nWhen milrinone was introduced, it caused an increase in heart rate across all age groups, but the effect was most noticeable at high doses. Milrinone also enhanced the heart's contractility and relaxation, but the strength of this effect depended on the heart's age and was lessened when the heart was being paced at a high frequency.\n\nAdult hearts showed the greatest increase in left ventricular pressure during normal rhythm and had a robust response to high doses of milrinone, which was less marked in neonatal hearts. The action potential duration and calcium transient duration were shorter in both neonatal and adult hearts, but showed minimal changes in juveniles, indicating a non-uniform developmental pattern.\n\nThe study concludes that milrinone has positive effects on the heart's rate, strength, and relaxation in all age groups, but the extent and sensitivity to milrinone's effects can vary with age. This suggests that the heart's maturity plays a significant role in how it responds to milrinone, highlighting the importance of considering a child's age when choosing and dosing this medication.",
  "summary": "Background: Milrinone, a phosphodiesterase-3 (PDE-3) inhibitor, is widely used to improve cardiac output in pediatric and adult patients. Yet, developmental differences in myocardial responsiveness to milrinone remain incompletely understood. In this study, we examined the impact of postnatal maturation on the acute cardiac effects of milrinone using an intact guinea pig heart model. Methods:…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}