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Effect of extracellular sodium on mechanical function in the newborn rabbit. 1981

T Nakanishi, and J M Jarmakani

The effect of high extracellular sodium concentration ([Na]o) on myocardial mechanical function was determined in the isolated, arterially perfused new born and adult rabbit heart. The muscles were initially perfused with hyperosmolar solutions containing 116 mM mannitol and all subsequent manipulations were done without changing the osmolarity. The inotropic effect of hyperosmolarity in the new born was significantly greater than that in the adult. Solutions containing 200 mM [Na]o caused immediate depression in myocardial contractility and this was followed by a partial recovery. The transient depression and recovery of myocardial contractility induced by 200 mM [Na]o alone was reduced so that the [Ca]o/[NA]o ratio was equal to that of 200 mM [Na]o solutions, the decrease in myocardial contractility in the new born was greater than that in the adult. These data suggest that: (1) the negative inotropic effect of high [Na]o is due to Na-Ca competition for external membrane binding sites, this effect in the newborn is greater than that in the adult; (2) the increased [Na]i stimulates Na-Ca exchange and increases Ca influx, this effect in the newborn is greater than that in the adult, and (3) the age-related difference in the effect of high [Na]o on myocardial contractility is, at least in part, related to the difference in the effect of calcium on mechanical function.

UI MeSH Term Description Entries
D006982 Hypertonic Solutions Solutions that have a greater osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Hypertonic Solution,Solution, Hypertonic,Solutions, Hypertonic
D009200 Myocardial Contraction Contractile activity of the MYOCARDIUM. Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D003864 Depression, Chemical The decrease in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical. Chemical Depression,Chemical Depressions,Depressions, Chemical
D004558 Electric Stimulation Use of electric potential or currents to elicit biological responses. Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D000831 Animals, Newborn Refers to animals in the period of time just after birth. Animals, Neonatal,Animal, Neonatal,Animal, Newborn,Neonatal Animal,Neonatal Animals,Newborn Animal,Newborn Animals
D012964 Sodium A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23. Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor

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