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Biomedical subjects

R J Baskin

Publications and source records attributed to R J Baskin.

At least 73 records · Page 4Linked to original sources
PubMed1971

Ultrastructure and calcium transport in crustacean muscle microsomes.

Fragmented sarcoplasmic reticulum (FSR) from crustacean muscle was examined following preparation by a variety of electron microscopic techniques. The 30-40 A particles which appeared on the outer surface of FSR vesicles following negative staining were not observed following preparation by freeze-drying, freeze-etching, thin sectioning, or critical-point drying. Crustacean FSR exhibited high values of calcium uptake and extensive nodular formation in the presence of oxalate. 80-90 A diameter membrane particles were seen in freeze-etch preparations of both intact lobster muscle and FSR vesicles. Thin sections of FSR vesicles revealed a membrane thickness of 60-70 A. The membrane appeared to be triple layered, each layer having a thickness of 20-25 A.

Adenosine Triphosphatases↗
PubMed1969

Ultrastructure of sarcoplasmic reticulum preparations.

Fragmented sarcoplasmic reticulum (FSR) from rabbit muscle was examined by positive staining, negative staining, and freeze-etch electron microscopic techniques in the absence and presence of calcium transport conditions. The existence of 30-40 A particles covering the outer surface of FSR vesicles was confirmed by two different negative stains in unfixed, glutaraldehyde-fixed and osmium tetroxide-fixed material. Freeze-etch microscopy revealed a second type of particle, 80-90 A in diameter, on the fractured surfaces of FSR vesicles. Following calcium oxalate accumulation, negative and positive staining techniques provided evidence for large nodular deposits within FSR vesicles which probably correspond to calcium oxalate crystals and are responsible for increments in turbidity during calcium oxalate accumulation. The most probable configuration of FSR vesicles in solution is spherical. "Tadpole" or tubular configurations were not seen by freeze-etch microscopy, positive staining, or in prefixed negatively stained material.

Animals↗
PubMed1966

Muscle volume changes.

Measurements have been made of the volume changes accompanying single isometric and isotonic twitches of frog sartorius muscle. The volume change consists of a rapid increase, a subsequent decrease, and a return to the initial volume; the order of magnitude of increase and decrease is 10(-5) cc/g of muscle. This volume change is length-dependent: the initial increase becomes more pronounced as the initial length of the muscle is decreased, while the volume decrease is greatest at reference length and is diminished for longer and shorter initial lengths. Muscle volume changes are also dependent upon temperature and amount of shortening: the return phase is prolonged as the temperature is lowered; and, in an isotonic twitch, a volume increase accompanying muscle shortening is superimposed upon the volume change described for an isometric twitch. These "shortening volume changes" may correspond to the volume decrease observed in frog muscle under a passive stretch. If the active state is prolonged by the use of a frog Ringer solution in which iodide ions have been substituted for chloride ions, the time course of the volume decrease is likewise prolonged; this suggests a relationship between the volume decrease and the active state of the muscle.

Animals↗
PubMed1965

The variation of muscle oxygen consumption with velocity of shortening.

Total oxygen consumption following contraction at controlled shortening velocities was determined for ten twitches of frog sartorius muscle. Under the conditions of this investigation maximum oxygen consumption occurred at approximately 30 mm/sec. shortening velocity and decreased for larger and smaller velocities. Mechanical efficiency was calculated and found to show a maximum at approximately 20 mm/sec. shortening velocity. The relationship between this study and a similar investigation in which heat changes are measured as a function of shortening velocity is discussed.

Animals↗