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Biomedical subjects

R K Entrikin

Publications and source records attributed to R K Entrikin.

33 records · Page 2Linked to original sources
PubMed1983

Water deprivation: beneficial effect on muscular dystrophy in chickens.

Chicks affected with hereditary muscular dystrophy were deprived of water for 1 to 4 days at ages to 37 days ex ovo. Water deprivation partially alleviated impaired righting ability and reduced the typically elevated plasma creatine kinase activity by as much as 90%. Muscles from water-deprived chicks showed several qualitative histologic improvements, including decreased sarcoplasmic staining for acetylcholinesterase activity, reduced fiber diameters, and a decreased incidence of abnormally large rounded fibers, but retained the high degree of fiber diameter variability characteristic of dystrophic muscles. Feed deprivation reduced body weight to a similar extent as water deprivation but had lesser effects on creatine kinase activity and did not improve righting ability or muscle histology. Although the mechanism of the improvements is unknown, the magnitude and scope of the effects suggest that water deprivation beneficially alters a major abnormality in dystrophic chickens.

Animals↗
PubMed1979

Suppression of myotonia in dystrophic chicken muscle by phenytoin.

We describe myotonic electromyographic activity in muscles of genetically dystrophic chickens and show that this activity is antagonized in vivo by doses of phenytoin (DPH) that improve righting ability. To test the possibility that the in vivo effects of DPH can be accounted for by a direct action on skeletal muscle we studied posterior latissimus dorsi fibers in vitro at 23 degrees C with intracellular microelectrodes. Compared to normal fibers, fibers from untreated dystrophic chicks had larger diameters, increased membrane capacitance, longer latencies at rheobase, and a greater tendency to fire repetitively in response to direct stimulation. DPH (10 or 50 micrograms/ml in the bath solution) decreased latencies at rheobase and repetitive firing in fibers from untreated chicks. In DPH-free solution fibers from dystrophic chicks treated chronically with DPH were still abnormal with respect to latencies at rheobase and ease of repetitive firing. The data support the hypothesis that abnormalities of membrane electrical properties are major features of dystrophic chicken muscles and furthermore, show that DPH suppresses, but does not abolish, these abnormalities.

Animals↗
PubMed1978

Effects of phenytoin on acetylcholinesterase activity and cell protein in cultured chick embryonic skeletal muscle.

Cultured pectoral muscle from 11-day-old chick embryos was treated for 48 h with phenytoin (diphenylhydantoin, DPH) in concentrations ranging from 15 to 270 microgram/ml on days 7-9 in vitro. Acetylcholinesterase (AChE, EC 3.1.1.7), creatine phosphokinase (CPK, EC 2.7.3.2), and lactic dehydrogenase (LDH, EC 1.1.1.27) activities, [3H]leucine incorporation into protein, and total protein of the cultures decreased in a dose-related manner with DPH concentrations of 30 microgram/ml and greater. Total AChE activity and AChE activity released into the medium were specifically decreased with 15 microgram DPH per millilitre. In cultures treated chronically with 15 microgram DPH per millilitre on days 5-13 in vitro, total AChE activity and AChE activity released into the medium were 66.0 +/- 13.2 and 64.7 +/- 11.8% of untreated controls, respectively, but cellular AChE activity, cell protein, and [3H]leucine incorporation into protein were unaffected. The results indicate that DPH specifically decreases the total net synthesis of AChE activity by a direct action on cultured chick embryo muscle.

Acetylcholinesterase↗
PubMed1977

Avian muscular dystrophy: functional and biochemical improvement with diphenylhydantoin.

Chicks affected with hereditary muscular dystrophy were injected twice daily with 20 milligrams of diphenylhydantoin per kilogram of body weight on days 1 to 40 after hatching. The righting ability of dystrophic chicks treated with diphenylhydantoin was improved compared to that of untreated dystrophic chicks, and acetylcholinesterase activity was reduced to normal levels in the posterior latissimus dorsi muscles.

Acetylcholinesterase↗
PubMed1975

Electrophysiological properties of biventer cervicis muscle fibers of normal and roller pigeons.

Cable parameters, excitability characteristics, and contractile response to acetylcholine were measured in biventer cervicis muscles from Helmet pigeons, Racing Homer pigeons and Parlor (nonflying) Roller pigeons. Cable parameters for the three strains, were respectively: calculated diameter, 30.1, 42.5, and 37.3 mum; membrane resistance, 450, 556, and 386 omega-cm2; membrane capacitance, 4.2, 3.9, and 4.5 muF/cm2, and myoplasmic resistivity, 79, 185, and 116 omega-cm. Significant differences between excitability characteristics of Homer pigeon and Roller pigeon fibers were a 17% shorter maximal latency for spike initiation (P less than 0.025) and 24% lower rheobasic current (P less than 0.05) in Roller fibers. Dose-response curves of isolated biventer cervicis to acetylcholine revealed slight, but significant, differences between Helmets and Rollers. These are the first electrophysiological data from pigeon skeletal muscle and the first from any avian biventer cervicis. The biventer muscles of chickens contain mainly "slow" fibers, but our results show that pigeon biventer fibers have properties similar to the "fast" PLD fibers of the chicken. Furthermore, the existence of different myoplasmic resistivities for each strain of pigeons used in this study suggests the need for more careful determination of this parameter in electrophysiological investigations. Although our results show that Roller pigeon fibers differ from those of nonrolling pigeons in the respects described above, these differences are minor in comparison to the severe behavioral abnormalities of Roller pigeons. Some yet untested component of neuromuscular transmission may be directly involved in the rolling phenomenon, but the differences we report may simply be due to strain differences, muscle hypertrophy, or a more severe defect elsewhere in the nervous system.

Acetylcholine↗
PubMed1975

Myotonia and block of chloride conductance by iodide in avian muscle.

Immature chickens and adult pigeons whose drinking water contained 3% KI for 1--10 days developed myotonia, characterized by stiffness on sudden movement and abnormal repetitive firing of skeletal muscle fibers. Component resting membrane conductances, excitability, and membrane potentials of biventer cervicis muscle fibers from adult pigeons were measured in vitro at 38--39degreesC. Fibers from iodide-treated pigeons in normal solution and fibers from untreated pigeons in I--containing solution (15--120 mM) responded repetitively to electrical and mechanical stimulation. Resting anion conductance (Ganion), assumed to be the sum of C1- and I- conductances, of fibers from iodide-treated pigeons decreased nonlinearly from 2,565 to 266 mumho/cm2 when the bath concentration of I- was increased from 0 to 120 mM. Potassium conductance was assumed constant at 577 mumho/cm2. Ganion of fibers from iodide-treated pigeons was 50% of control and equaled that of untreated fibers in 15 mM I- containing medium. Reduction of the stabilizing Ganion and increased mechanical responsiveness can account for the iodide-induced myotonia in birds.

Animals↗
PubMedDate not supplied

Myotonic electromyographic activity in complexus muscles of normal and dystrophic chicks.

Myotonic-like, "dive-bomber" discharges were recorded from complexus ("hatching") muscles of both normal and dystrophic chicks at 5 days ex ovo and were recordable from dystrophic, but not from normal, pectoralis major muscles at 28 days ex ovo. The complexus muscle, therefore, provides the opportunity to study in young, normal animals, a form of electrophysiological activity previously considered a sign of neuromuscular abnormality.

Age Factors↗