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Related post: consist in stimulation, with subsequent paralysis, being similar to the effects of asphyxia. Salt Action on Phagocytosis. The sensitiveness of cells to small changes in osmotic concentration is shown by the phagocytic power of leucocytes. According to H. Ham- burger and his pupils, 1908 and 1910, the phagocytic power is decreased by very small changes of the osmotic concentration of the serum, such as may occur under physiologic conditions. All anisotonic solutions are injurious, but especially increased concentra- tions. The leucocytes recover when the normal concentration is Buy Promethazine Online restored. NaCl causes but little Purchase Promethazine Online injury apart from the Generic Promethazine osmotic effect. Nal is more toxic than NaBr. Of other ions, a slight excess of calcium stimulated, while decreased activity resulted from a larger excess, and from reduction of calcium as by fluorids or citrates. Ba and Sr do not Buy Promethazine have the stimulant action, so that it is not due to valence. Diminution of the normal alkalinity was deleterious, and to a less Cheap Promethazine degree also an excessive alkalinity. Osmotic Response of Muscle. Striped muscle is semipermeable, smooth muscle is permeable. This different permeability is reflected in their response. Immersion in water, /./., causes striped muscle to become rigid and to shorten, smooth muscle to lengthen. The effects are counteracted by 2 per cent. NaCl (Meigs, 1912). Dale, 1913, also found the tone of smooth muscle increased by hypo- and diminished by hyper- tonic Ringer's solutions. Slightly hypertonic solutions increased the response to in- hibitory drugs and decreased the effects of stimulant drugs. Slightly hypotonic solu- tions had the opposite effect. The muscle of the Venus agrees with non-striated muscle, in being permeable (Meigs, 1914). Faligue increases the molecular concentration (depression of freezing point) of excised skeletal muscle by 36 per cent, by the breaking down of molecules. This does 638 MANUAL OF PHARMACOLOGY not occur when the circulation is intact, for the differences are then equalized by ex- change with th-j blood (A. R. Moore, 1916). Ion Effects on Muscle. The immersion of muscle in various solutions produces marked effects even when osmotic changes are excluded by having the solutions isotonic. These must therefore be referred to ion actions. The muscles lengthen or shorten; the excitability may be diminished or increased; spontaneous rhythmic contractions may appear ; or the mus- cle may develop "contact irritability" so that it will react to stimuli which are ordinarily ineffective. Invertebrate and mammalian muscles, exhibit similar phenomena if proper conditions are maintained. ACTIONS OF ELECTROLYTES Importance of Electrolytes. Muscles soon lose their excitability com- pletely in solutions of non-electrolytes; but this returns when they are replaced in saline solutions. A medium containing electrolytes is there- fore essential to muscular contraction; indeed, any change in the ions Promethazine Online pro- duces alterations in the muscular functions. The different ions are not equally effective. It appears that the nature of the cathions is more important than the anions. The ions arrange themselves in the usual lyotropic series, the Na and I end being the most favorable, and the K and citrate end being the most unfavorable. Toxic Action of Single Salts. Immersion in any solution of a single salt also renders muscle inexcitable, but with very different rapidity. These differences follow the lyo- tropic series in the same sense. Rhythmic Contractions of Skeletal Muscle. These generally develop before the irritability is lost, when muscle is immersed in solutions of a single electrolyte (Loeb, 1899). If a certain proportion of a calcium salt is added, the rhythmic property dis- appears again. The rhythmic contraction of the cardiac muscle or of medusae also dis- appears when calcium is added. Rhythmic contractibility is not therefore a property characteristic of cardiac muscle, but is inherent in all muscular tissues. The reason why the contraction of the heart is ordinarily rhythmic, and that of skeletal muscle not, lies in the fact that the ions in the heart are balanced so as to favor rhythmic contrac- tions, Order Promethazine and in the skeletal muscle they are not so balanced. Ciliary and Muscular Movement. R. S. Lillie (1902) has studied the effects of ions on the larvae of a sea- worm (Arenicola), which executes both ciliary and muscular movements. He found that the presence of magnesium in the mixture favors the con- traction of the cilia, calcium of the muscles; potassium hinders both. Parker (1905) has found that potassium reverses the stroke of certain cilia. Ion Actions on Heart. These are highly important to the cardiac Buy Cheap Promethazine contractions. The excised hearts of cold-blooded animals soon stop their beat when immersed in solutions of non-electrolytes (Carlson); but they continue to contract rhythmically for a long time in certain salt solutions. Analogous phenomena are observed in the perfusion of mammalian hearts. The solutions must contain Na, K, and Ca ions; and these must be in a fairly definite "balanced" ratio, as in Ringer's or Locke's solutions or their modifications. Deficiency or excess Purchase Promethazine of these ions cause derange- ment of function and are equally fatal. The ratio is much more impor- tant than the absolute quantity of the ions. The anions are relatively indifferent. R61e of the Individual Cathions. NaCl is indispensable to the rhythmic contractions of the heart; but when present alone it produces relaxation and is finally fatal to the heart as to other tissues. The addition of K ions produces a diastolic tendency and standstill. Ca and NaCl produce increased systolic contractions but the diastoles ACTIONS OF ELECTROLYTES 639 become imperfect and deficient. Starting with a balanced Ringer's solution, sudden increase of K results in slowing and weakening (often halving of the rate), and decreased excitability to vagus stimulation, and with higher concentrations in arrest. This may be removed by the injection of Ca, or by accelerator stimulation. Increase of Ca acts like accelerator stimulation, resulting in increased excursions, prolongation and fusion of systoles, and systolic standstill. Ca is also necessary for the inhibitory response to vagus stimulation; but excessive Ca concentration paralyzes the vagus (Schiff ; Cazzola, 1913; Boehm, 1914). The K or Ca actions predominate when the percentage of one predominates about three and one-half times over the other. The effects of K-free Ringer's solution resemble Ca predominance. Ca-free Ringer's solution increases the rate i.e., the result is the opposite of K in the presence of Ca. Deficiency of Ca, K or OH ions shortens the survival of the heart (Boehm, 1914). Theories of Cardiac Ion Relations. In the light of these data attempts have been made to assign definite functions to the individual ions. They are not very satisfac- tory, except in that they emphasize that Ca and K have opposite and complementary effects (Ringer, 1882), Ca for promoting contraction and K relaxation. Loeb, 1899, attributed the contractions to the Na ions, but requiring the presence of Ca. Howell, Order Promethazine Online 1898 and 1906, believes that Ca is concerned in the contraction and K and Na in the relaxation; that these ions enter alternately into relation with the contractile substance; that accelerator stimulation liberates Ca and vagus stimulation K ions. Martin, 1913, assumes with Howell that Ca promotes the conversion of stable into unstable energy- yielding material; that Na brings about the actual dissociation and thus initiates the beat (Lingle); and that K antagonizes both the Na and Ca. The chemic conditions of cardiac activity are reviewed by Tigerstedt, Erg. Physiol., 12: 269.
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