Preparation of specific immune sera against rabbit skeletal, pig and human cardiac heavy meromyosins

Antibodies were produced in guinea-pigs against heavy-meromyosin (HMM) and tested by immunodiffusion and microcomplement fixation (MCF). A similar response was obtained for HMM extracted either from human and pig left ventricles, or from rabbit white skeletal muscles. For each muscle, the antisera cross-react quantitatively with the native intact myosin and are highly specific. Thus, this procedure permits the preparation of muscle type-specific anti myosin antibodies, by a simpler means than those previously published.

A comparative study of skeletal and cardiac tropomyosins: subunits, thiol group content and biological activities

The subunit composition, the thiol group content and the biological activities of cardiac tropomyosins (TM) of various animal species were compared. Cardiac TM from small animals such as rabbit, guinea-pig, rat and dog contain 2 SH/mole and were resolved into one band on SDS and acid urea electrophoresis and into two bands on alkaline urea electrophoresis. Chicken cardiac TM likewise gave one band and it contains 4 SH/mole. In contrast pig, sheep and human cardiac TM contain respectively 2.6, 2.4, and 2.4 SH/mole and were resolved into two bands alpha and beta on the different electrophoresis systems used, with a beta:alpha ratio respectively of I:4.2, I:4.6, I:4.8. The alpha-TM components from sheep skeletal and pig and sheep cardiac muscles were more positively charged than the rabbit skeletal alpha-TM component, as shown in alkaline urea electrophoresis system. The alphaalpha and alphabeta combinations of dimers found for skeletal muscle by other authors, were also found for cardiac pig TM. All the TM have the same effect on the Ca2+-stimulated ATPase activity of desensitized actomyosin (DAM) and on the Mg2+-stimulated ATPase activity of DAM with troponin-complex. This work suggests that the subunits of the TM from skeletal and cardiac muscles are heterogenous in their M.W. and their charges and that in the heart as well as in skeletal muscle a relationship seems to exist between the amount of the beta component and the speed of contraction of the muscle: a higher amount of this component was found in the bulky hearts which are also those which contract slower.

Heart contractile proteins

That several proteins of the sarcomere differ from one muscle to the next is well documented, and it is becoming evident that homogeneous muscles, like the heart, are also species specific. 1) Clear-cut evidence is available concerning myosin, and, to date, several types of molecules have been described. a) The myosins of white skeletal, heart, and smooth muscle differ in the activity of their Ca2+ and K+ATPases, as also in the structure of their light subunits. b) The Ca2+ATPases of the various cardiac myosins have been shown to exhibit species differences and correlate with the speed of shortening of the muscle. 2) The structures of tropomyosin, some troponin components, and alpha actinin (but not actin) appear to be unlike in the different types of muscle. 3) These phylogenic modifications may be related to the changes characteristic of the particular muscles under pathological conditions, which are accompanied by substantial increase in protein synthesis.

Polarized Magnetic Field Fluctuations at the Apollo 15 Site: Possible Regional Influence on Lunar Induction

High-frequency (5 to 40 millihertz) induced lunar magnetic fields, observed at the Apollo 15 site near the southeastern boundary of Mare Imbrium and the southwestern boundary of Mare Serenitatis, show a strong tendency toward linear polarization in a direction radial to the Imbrium basin and circumferential to the Serenitatis basin, a property that could be indicative of a possible regional influence on the induction.

Blood Oxygen Capacity

During determination of the oxygen capacity of blood by the Van Slyke method (1), the following adaptations were made in order to reduce errors: (1) Blood was equilibrated with water-saturated air in a siliconized tonometer. (2) The determination of the oxygen content of the sample was carried out immediately after equilibration. (3) Triton was used instead of saponin in the ferricyanide reagent. (4) Special care was taken in the preparation and storage of the dithionite reagent, which should be prepared fresh daily and stored in the dark at 4°. The hemoglobin content and oxygen capacity, measured by the modified technic, were compared in a series of 36 samples of human blood.