Postnatal development of cardiac distribution in the pig.

Distribution of cardiac output was measured in 0- and 12-hour-old piglets using 103Ruthenium-labelled microspheres, 15 +/- 3 micrometer in diameter. The 12-hour-old piglets had remained with the sow and had suckled. Coronary and bronchial fractions of cardiac output were high in piglets at birth. The coronary fraction remained high at 12 h but the bronchial fraction decreased significantly (p less than 0.05). Percent cardiac output to the liver and upper gastrointestinal tract, pancreas and salivery gland in 12-hour-old piglets was significantly increased (p less than 0.01) by 138, 156, 85 and 109%, respectively, compared with piglets at birth. Preferential blood flow occurred to the lungs, adrenals, heart, thyroid and spleen at 0 h and to the adrenals, thyroid, heart, lungs and diaphragm at 12 h.