Cardiovascular responses to feeding in newborn piglets.
Cardiovascular responses to feeding have been observed in several species during various periods of development and have been implicated in the development of cardiovascular regulation. In the rat, these responses are characterized by short-lasting, large increases in blood pressure (BP) and moderate increases in heart rate. These responses appear to be sympathetically mediated because pretreatment with ganglionic blockers eliminates the increase in BP associated with milk ingestion. The present study was designed to determine if similar cardiovascular responses occur during feeding in the newborn piglet. Piglets were obtained on postnatal d 2 and fed a milk diet via automatic feeder 6 times a day. On postnatal d 6, the piglets were instrumented with an external carotid artery catheter and an internal jugular vein catheter. On postnatal d 8 and 9, direct arterial BP and heart rate were recorded during feeding. BP responses to milk ingestion were immediate, and they reached a maximum increase of 50% above baseline on both test days and followed a response profile similar to that previously described in the 15-d-old rat. An increase in heart rate was also observed, reaching a maximum of 42% above baseline. The results show that early in life piglets have large cardiovascular responses to milk ingestion similar to those observed in young rats and human infants. These responses appear to model the cardiovascular responses to feeding observed in human infants and might be useful as a noninvasive method for assessing neonatal autonomic reactivity. These responses also have the potential to cause adverse effects in newborns already at risk for cardiovascular and cerebrovascular disease.
Division of Reproductive and Developmental Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079.
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D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D002319:Cardiovascular System / Q000187:drug effects; D004435:Eating / Q000502:physiology*; D005730:Ganglionic Blockers / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008892:Milk; D013552:Swine; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology
D005730:Ganglionic Blockers; D006584:Hexamethonium Compounds; D018738:Hexamethonium