ACTION OF STRONTIUM IONS ON THE ISOLATED HEART OF THE RAT AND GUINEA PIG
Addition of 2.1 mM/l Sr/sup ++/ (as SrCl/sub 2/) to the saline solution bathing rat heart progressively lowers the amplitude of contraction, to approximates 15% below normal within 10 min. This inhibition is preceded by a slight, transient stimulation of contraction. Inhibition is reversible if Sr/sup ++/ is removed within 4 to 5 min. In guinea pig heart under the same conditions, Sr/sup ++/ produces greater inhibition; amplitude is reduced 30% after 6 min., without a preliminary positive inotropic effect. If 90% of the Ca/sup ++/ ions in the salt solution are replaced by Sr/sup ++/, Sr/sup ++/ completely compensates for the lowering of Ca/sup ++/ concentration, indicating that it is completely equivalent to Ca in promoting contractility of rat heart muscle. However, in guinea pig heart the tonotropic action of Sr/sup ++/ was proportionally greater than that of Ca/sup ++/. Thus, at low Ca concentrations rat heart is more sensitive to Sr/sup ++/ than guinea pig heart. In the absence of Ca/sup ++/, Sr/sup ++/ stimulntes contraction to such an extent in both species that the excessive tonus practically abolishes heart action. It appears that Sr/sup ++/ cannot totally replace Ca/sup ++/ in the cardiac contractile mechanism. (H.H.D.)
- Research Organization:
- Faculte des Sciences, Paris
- NSA Number:
- NSA-17-005686
- OSTI ID:
- 4751641
- Journal Information:
- Compt. Rend. Soc. Biol., Vol. Vol: 155; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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