The response of the new‐born piglet to an excess of potassium

Abstract

In experiments on the nitrogen metabolism of piglets during the first days of life (McCance & Widdowson, 1956) some of the piglets were given an evaporated cow's milk mixture. This contained more sodium, chloride and potassium than sow's milk, and piglets having it developed hypertonic expansion of the extracellular fluids. This was more fully investigated by McCance & Widdowson (1957), and it was then shown that human infants reacted in a very similar way. The animals in the first experiments also retained more potassium from the cow's milk mixture than they appeared to require for co-ordinated growth. The interest of this is not confined to piglets, for something similar has been shown to take place in human infants (M. 0. Beem & C. A. Smith, personal communication). Further experiments therefore were designed to study this retention of potassium under more controlled conditions than were possible in 1956. The experiments were planned on the lines of those carried out on sodium chloride loading and are reported in this paper. METHODSThe general arrangements were the same as those described by McCance & Widdowson (1956 and only special points need be described in detail. Three litters have been used. Each has been treated in an almost identical manner and all have given similar results. The first piglet in each litter was given water, and the second an equal volume of water to which KCI (120 m-equiv/l.) had been added. This contained the same concentration of chloride as the 0 7 % NaCI solution used in the previous experiments (McCance & Widdowson, 1957). The third piglet was given a volume of sow's milk times as great as the volume of water. This made the intakes of water about equal since the sow's milk used contained 15-20% of solids. The fourth piglet was given a volume of sow's milk equal to that given to the third, but KCI was added to make the concentration of potassium in the water of the milk equal to the concentration of potassium in the water given to the second piglet. This made the potassium intake of piglets two and four about the same and roughly three times that of the third piglet, which was having sow's milk. These piglets were fed two-hourly as before. The fifth piglet was given nothing.The experiments, like the ones on sodium chloride, lasted for 40 hr and the urines were again

Development of Renal Potassium Excretion Capacity in the Neonatal Rat.

“…As expected, the potassium excretion rates in the potassium-loaded groups were much higher than those of the minimum potassium excretion for the same age determined in the no-potassiumloaded group. Our findings are consistent with previous studies presenting that under certain conditions, i.e., after dietary potassium loading, the healthy premature infants can excrete potassium at a higher rate than it is filtered [3] and that piglets in the first day of life could excrete most potassium chloride (KCl) given by stomach tube [13]. In the present study, the renal potassium excretion rate quickly changed in response to the oral potassium load and the elder rats could excrete more potassium within a shorter period.…”

“…Thus the renal potassium excretion capacity was directly compared with an obligatory potassium excretion (OPE), which is defined as the difference between daily potassium intake and estimated potassium accumulation in the ICF (APPEN-DIX). This is because in the younger rats, most potassium in milk was accumulated in the intracellular fluid (ICF), which may be undergoing rapid growth [13]. The changes in potassium content in the ECF were assumed to be negligible because more than 98% of body potassium is accumulated in the cells (ICF) [1].…”

“…Moreover, numerous papers have reported that newborn animals, such as infants [3], piglets [13], and dogs [9] can excrete the exogenous potassium load. Thus high PK in the newborn animals may not be abnormal, but it may be the result of a physiological state of positive potassium balance for growth.…”

Ontogeny of flow-stimulated potassium secretion in rabbit cortical collecting duct: functional and molecular aspects

“…In response to exogenous K loading, infants, like adults, can excrete K at a rate that exceeds its filtration (55), indicating the capacity for net tubular secretion. However, the rate of urinary K excretion in K-loaded infants and young animals is less than that observed in older animals (27,29).…”

An unexpected journey: conceptual evolution of mechanoregulated potassium transport in the distal nephron

“…Cyclic guanosine monophosphate first 40 h of life. Whereas K-loaded animals provided water alone lost weight and experienced life-threatening hyperkalemia and paralysis, piglets fed the equivalent amount of K in milk grew well and remained normokalemic (127).…”