tannins and osteum

THE ACTIVITY OF FROG ISOLATED HEARTS WAS DEPRESSED BY ALTERING THE PERFUSING RINGER SOLUTION IN FIVE DIFFERENT WAYS: by reducing the calcium content, by increasing the potassium content, and by adding ether, thiopentone or acetylcholine. Depressed hearts were perfused with Ringer solution containing the following stimulant drugs: paullinia tannin, tannic acid, hydrogen peroxide, sodium oleate, sodium caprylate and ouabain. All these stimulant drugs had similar actions on hearts depressed by calcium lack, ether and thiopentone; hearts depressed by acetylcholine were, however, only weakly stimulated. Hearts depressed by potassium were readily stimulated by oleate, caprylate and paullinia tannin; ouabain and hydrogen peroxide had weak stimulant actions on hearts depressed by potassium, and tannic acid had a negative inotropic action. The differing actions on hearts depressed by potassium are probably related to differences in the degrees of fixation of the stimulant drugs. The mode of action of ouabain and the functional lesion in hearts depressed by narcotics are discussed.

Topics: Acetylcholine; Animals; Anura; Calcium; Calcium, Dietary; Caprylates; Central Nervous System Stimulants; Ether; Ethers; Heart; Hydrogen Peroxide; Oleic Acid; Ouabain; Pharmacology; Potassium; Research; Strophanthins; Tannins; Thiopental

Eight drugs that stimulate the isolated hypodynamic frog heart have been tested for their ability to stimulate hearts freshly perfused in calcium-free Ringer solution. Ouabain and digitoxigenin regularly caused stimulation, veratridine did so occasionally. Hydrogen peroxide, tannic acid, paullinia tannin (from Paullinia pinnata, Linn.), sodium oleate and sodium caprylate did not stimulate. The stimulant action of ouabain could be prevented or greatly reduced by prior perfusion with either of the two tannins or with hydrogen peroxide. Hearts perfused for 3 to 4 hr with calcium-free Ringer solution, or hearts perfused for shorter periods of time with calcium-free Ringer solution containing the disodium salt of ethylenediaminetetra-acetic acid, behave unusually in that when perfusion with low-calcium Ringer solution is resumed twitch tension does not return for periods ranging from 10 to 90 min. Ouabain is unable to stimulate these "calcium-depleted" hearts. It is suggested that hydrogen peroxide, the two tannins, oleate and caprylate stimulate by causing the heart to increase the uptake of calcium from the perfusion fluid to a superficial site where calcium is necessary for the propagation of excitation from the cell membrane inwards. A special feature of the action of cardiac glycosides may be their ability to enable the heart to utilize in a similar way the intracellular stores of calcium.

Topics: Animals; Anura; Calcium; Calcium, Dietary; Caprylates; Cardiac Glycosides; Glycosides; Heart; Hydrogen Peroxide; Oleic Acid; Ouabain; Ranidae; Tannins