Biomaterial Database

Developmental pattern of muscle fiber types in human ventilatory muscles. 1978

T G Keens, and A C Bryan, and H Levison, and C D Ianuzzo

Premature infants tolerate respiratory loads poorly. This may reflect incomplete development of the ventilatory muscles (VM) causing poor resistance to fatigue. To study the developmental pattern of human VM, 31 postmortem specimens of diaphragm and intercostal muscles were obtained. Individual muscle fibers were classified as type I (slow-twitch, high-oxidative) or type II (fast-twich, low-oxidative) using histochemical staining methods for myofibrillar adenosine triphosphatase (M-ATPase) (pH 10.30) and nicotinamide adenine dinucleotide (NADH) tetrazolium reductase. In the diaphragm, premature infants (less than 37 wk gestation) had only 9.7 +/- 1.3% type I fibers, full-term newborns 25.0 +/- 1.1%, and older subjects (greater than 2 yr of age) 54.9 +/- 1.3%. There was no further increase after 8 mo postpartum. In the intercostal muscles, premature infants had only 19.0 +/- 4.8% type I fibers, full-term newborns 45.7 +/- 1.3%, and older subjects 65.2 +/- 2.6%. There was no further increase after 2 mo postpartum. These findings suggest the ventilatory muscles of newborn infants are more susceptible to fatigue than those of older subjects. This may contribute significantly to respiratory problems in the neonate.

UI	MeSH Term	Description	Entries
D007223	Infant	A child between 1 and 23 months of age.	Infants
D007231	Infant, Newborn	An infant during the first 28 days after birth.	Neonate,Newborns,Infants, Newborn,Neonates,Newborn,Newborn Infant,Newborn Infants
D007366	Intercostal Muscles	Respiratory muscles that arise from the lower border of one rib and insert into the upper border of the adjoining rib, and contract during inspiration or respiration. (From Stedman, 25th ed)	Intercostal Muscle,Muscle, Intercostal,Muscles, Intercostal
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D009247	NADH, NADPH Oxidoreductases	A group of oxidoreductases that act on NADH or NADPH. In general, enzymes using NADH or NADPH to reduce a substrate are classified according to the reverse reaction, in which NAD+ or NADP+ is formally regarded as an acceptor. This subclass includes only those enzymes in which some other redox carrier is the acceptor. (Enzyme Nomenclature, 1992, p100) EC 1.6.	Oxidoreductases, NADH, NADPH,NADPH Oxidoreductases NADH,Oxidoreductases NADH, NADPH
D011808	Quinone Reductases	NAD(P)H:(quinone acceptor) oxidoreductases. A family that includes three enzymes which are distinguished by their sensitivity to various inhibitors. EC 1.6.99.2 (NAD(P)H DEHYDROGENASE (QUINONE);) is a flavoprotein which reduces various quinones in the presence of NADH or NADPH and is inhibited by dicoumarol. EC 1.6.99.5 (NADH dehydrogenase (quinone)) requires NADH, is inhibited by AMP and 2,4-dinitrophenol but not by dicoumarol or folic acid derivatives. EC 1.6.99.6 (NADPH dehydrogenase (quinone)) requires NADPH and is inhibited by dicoumarol and folic acid derivatives but not by 2,4-dinitrophenol.	Menaquinone Reductases,Reductases, Menaquinone,Reductases, Quinone
D012127	Respiratory Distress Syndrome, Newborn	A condition of the newborn marked by DYSPNEA with CYANOSIS, heralded by such prodromal signs as dilatation of the alae nasi, expiratory grunt, and retraction of the suprasternal notch or costal margins, mostly frequently occurring in premature infants, children of diabetic mothers, and infants delivered by cesarean section, and sometimes with no apparent predisposing cause.	Infantile Respiratory Distress Syndrome,Neonatal Respiratory Distress Syndrome,Respiratory Distress Syndrome, Infant
D002648	Child	A person 6 to 12 years of age. An individual 2 to 5 years old is CHILD, PRESCHOOL.	Children
D002675	Child, Preschool	A child between the ages of 2 and 5.	Children, Preschool,Preschool Child,Preschool Children