| RESEARCH PAPER
|Year : 1983 | Volume
| Issue : 2 | Page : 111-118
Influence of extracellular ions. on the positive inotropic effects of sodium fluoroacetate and dobutamine
MD Burande, RK Goyal, SC Verma
Sodium Fluorocetate (Na FAC, 20 'g to 320 'g) and dobutamine (.5 'g to 8 pg) produced dose dependent positive inotropic effect in isolated frog heart preparation, without affecting the heart rate. The responses to Na FAC and dobutamine were inhibited when calcium chloride (CaCl2) concentration was increased from 1.58 mM to 3.17 mM in frog Ringer solution. When Ca Cl2 concentration was reduced the responses to both Na FAC and dobutamine were potentiated. By reducing the potassium chloride (Kcl) concentration in the perfusion fluid (from 1.8 mM to 0.9 mM) the responses to Na FAC were potentiated, while increasing the concentration (from 1.8 mM to 3.6 mM) the responses were inhibited. However, the responses to dobutamine were unchanged by changing the Kc1 concentration in perfusion fluid. The decrease in sodium chloride (Na Cl) concentration (from 110mM to 55mM) in frog Ringer solution, inhibited the responses to Na FAC while increase in Na Cl chloride concentration (from 110mM to 165mM) potentiated the responses to Na FAC. However the responses to dobutamine were unchanged when Na Cl concentration in perfusion fluid were altered. It is suggested from the date that Na FAC induced positive inotropic effects were probably due to sodium extrusion mechanism leading to facilitation of calcium uptake, Dobutamine may be acting directly through the mechanism independent of extracellular ions.
M D Burande
Source of Support: None, Conflict of Interest: None