Sarcomere shortening in pressure overload hypertrophy

Sarcomere shortening during contraction was measured by using laser diffraction, in thin, rabbit right ventricular (RV) trabeculae from normal hearts (N) (n = 5) and from hearts subjected to RV pressure overload by pulmonary banding (H) (n = 5). Banding resulted in substantial RV hypertrophy after 2 wk. Hypertrophied preparations had the same resting muscle length (H = 3.15 +/- 0.29 mm) and resting sarcomere lengths (H = 2.16 +/- 0.005 micron) as the normal preparations (3.10 +/- 0.37 mm, 2.16 +/- 0.008 micron, respectively). Total tension at the peak of isometric twitches was the same as normal in the hypertrophied muscles (N = 8.06 +/- 1.20, H = 8.51 +/- 1.95 g/mm2). However, the amount of auxotonic sarcomere shortening was much less than normal in the hypertrophied preparations (N = 0.39 +/- 0.028, H = 0.19 +/- 0.034 micron; P less than 0.001). In isotonic contractions in which the ratio of muscle shortening to resting muscle length was the same in both the normal and hypertrophied muscles (ratio of 0.05 in both groups), the extent of sarcomere shortening relative to resting sarcomere length was less in the hypertrophied muscles than in the normal preparations (N = 0.14 +/- 0.01), H = 0.07 +/- 0.01; P less than 0.01). Series elasticity was the same as normal in the hypertrophied muscle P less than 0.05). Less auxotonic sarcomere shortening for a given level of isometric tension development and less isotonic sarcomere shortening per unit muscle shortening indicate that there is less than normal work per sarcomere during contraction in hypertrophied myocardium. These findings may have important implications for intracellular compensatory adaptation in pressure overload cardiac hypertrophy.     

The history of the United States Food, Drug and Cosmetic Act and the development of medicine

The future role of pharmacologists in the evaluation of drugs will increase as scientific knowledge and our understanding of drugs and disease processes increase. In addition, political issues and public fears will place further demands on the scientific community to try to influence the drug regulatory process. The FDA continually issues directives which guide all phases of drug development, from the identification of a chemical as being of potential interest on therapy, through all animal tests and clinical phases (4).     

Studies of the blood chemistry of Electrophorus electricus and a new physiological saline solution based thereon

Based upon analyses of the composition of electric eel blood serum we suggest a new physiological saline solution as follows: 188 mM NaCl, 5 mM KCl, 2 mM MgCl₂, 2 mM CaCl₂, 0.15 mM NaH₂PO₄, 1.45 mM Na₂HPO₄ and 5 mM glucose; pH 7.4. The major difference between this saline and that used in most of the previous investigations using eel electroplaques is that the total Na⁺ concentration is increased from between 162.7 and 171.7 mequiv/l to 191 mequiv./l. This increase does not appear to affect the electrophysiological properties of the electroplaque.