Lactate dehydrogenase isozyme patterns in the denervated quail (Coturnix coturnix japonica) muscles.

Polyacrylamide gel electrophoresis of the Japanese quail (Coturnix cotunix japonica) muscle extracts revealed a single lactate dehydrogenase isozyme. A month after surgical unilateral brachiotectomy (denervation) there was significant atrophy of the triceps, biceps and radius ulnar muscles accompanied by the appearance of an additional lactate dehydrogenase isozyme band. This extra band may be the result of the synthesis of a new lactate dehydrogenase isozyme. This new isozyme exhibited a lower affinity for lactate, less sensitivity to urea denaturation and was more thermostable than the lactate dehydrogenase of normal (innervated) quail muscles. Based on these properties, it is suggested that the newly synthesised isozyme of the denervated muscles is LDH-1 ,(or B4/H4) type. Brachiotectomy also resulted in significant quantitative changes in the total lactate dehydrogenase activity of innervated muscles of the same animal.

Ultrastructural variations in frog muscles subjected to sciatectomy.

Fine structural variations in two different types of muscles of frog (Rana cyanophlictis) subjected to sciatectomy were studied electronmicroscopically. Gastrocnemius muscle showed marked myofibrillar disarray and degeneration due to sciatectomy, while sartorius muscle was relatively less affected. The extent of sciatectomy induced fine structural variation was in proportion to the degree of denervation atrophy (as reflected by loss of wet muscle weight) in these muscles. Differences in the degree of degenerative changes in atrophying muscles may be attributed to variations in fiber type composition and stretch effects imposed during swimming movements.

Changes in ascorbic acid content and acetylcholinesterase activity in the muscle of frog following sciatectomy.

Unilateral-sciatectomy for three months in the frog, Rana cyanophlictis resulted in a substantial increase on unit weight basis in the ascorbic acid (ASA) and dehydroascorbic acid (DHA) contents of the sciatectomized gastrocnemius muscle. Diketogulonic acid (DKA) levels did not vary. On whole muscle-weight basis only the ASA level increased. The AChE activity in sciatectomized muscle is significantly lower than that of the control. Partially purified preparation of the AChE from the sciatectomized muscle showed different kinetics compared to that from innervated control. In vitro additions of ASA in physiological concentration to the enzyme assay medium inhibited the AChE activity significantly and the inhibition was an un-competitive type. Reduced activity of the enzyme has been correlated to the increased concentration of ASA in the sciatectomized muscle.

Electrocardiographic changes on sublethal poisoning of Vacor and Silmurin to Bandicota bengalensis.

A single sublethal dose of Vacor (1 mg/rat) or Silmurin (50 microgram/rat) brought about dissimilar changes in cardiac physiology of bandicoot rats. Delayed myocardial repolarization and stress on cardiac tissues were noticed. Elevation of S-T segment above the isoelectric axis diagnostic of recent myocardial infarction was observed. Vacor and Silmurin induced differential changes in heartbeat; Vacor poisoning resulted in bradycardia, whereas Silmurin tachycardia. It is inferred that Vacor deaths may be due to bradycardia associated with atrioventricular block and that of Silmurin to delayed myocardial repolarization and tachycardia.

Synthesis in vitro of cholesterol by mitochondria in the shrimp Penaeus aztecus (Ives).

The incorporation of [ 14C ]-acetate, [ 14C ]-mevalonate and [ 14C ]-desmosterol into cholesterol in the muscle mitochondria of the brown shrimp Penaeus aztecus (Ives) is more as compared to that in hepatopancreas. [ I4C ]-Desmosterol is more efficiently incorporated into cholesterol in comparison with [ 14C ]-acetate. The muscle mitochondria from males incorporated more [ 14C ]-mevalonate into cholesterol than those from females, while the converse is true in the hepatopancreatic mitochondria.

Non-competitive inhibition of serum acetylcholinesterase (E.C.3.1.1.7) by vacor (N-3-pyridyl methyl-N'-P-nitrophenyl urea) in bandicoot rats.

Single dose (1 mg/rat) administration of VACOR (N-3-pyridyl methyl-N'-nitrophenyl urea) produced significant paralytic symptoms in rats. Such rats which lived for one week were sacrificed and serum AChE was extracted and purified by Sephadex column chromatography. The serum enzyme from the normal rats showed the existence of two isozymes on polyacrylamide gels which could be resolved through column chromatography. Both the isozymes showed non-competitive inhibition with VACOR in vitro; but to a varied degree. The ACh concentration increased by 70-75% in serum and 95-100% in erythrocytes of the poisoned rats. VACOR thus affects ACh hydrolysis thereby causing an accumulation of ACh in the serum of poisoned rats.

Ca2+-ATPase activity and lipid composition of sarcoplasmic reticulum of the gastrocnemius muscle of denervated frog.

Abnormalities have been noticed in the phospholipid and cholesterol composition of the atrophied gastrocnemius muscle of frog denervated for 1 month. Cholesterol : phospholipid molar ratios in the muscle increased on denervation. Sphingomyelin and cardiolipin fractions increased in contrast to phosphatidyl choline, phosphatidyl serine and phosphatidyl ethanolamine in the sarcoplasmic reticulum (SR) of denervated muscle. Na-azide sensitive Ca2+ ATPase activity of the mitochondria did not alter whereas that of SR decreased on denervation. Phospholipase C digestion impaired the organelle Ca2+-ATPase activity. The above abnormalities in enzyme activities have been correlated to the changes in the lipid composition of the denervated muscle. On the basis of these changes it is discussed that the primary change in the muscle due to denervation is the change in the permeability of the membrane.