Many studies have been conducted on the toxicity of metylmethacrylate monomer. Methylmethacrylate monomer has been known to cause physiological and histological changes in ·various organ systems. Particularly well-known are its effect on the vascular system and blood pressure. However, pharmacological effect of the monomer on the caidiac muscle, especially its directaction on the contractility and excitability, and on acid-base balance has not been clarified.
In the present study, pharmacological effect of the monomer on the cardiac function was investigated through the measurement of contraction forces, maximal dT/dt and latency with Physiograph and its accessories in the turtle heart perfused with turtle Ringer solution containing the monomer liquid. Acid-base parameters, respiration, blood pressure and heart rate were measured with Physiograph in rabbits after intravenous injection and during continuous infusion of the monomer. Arterial blood was sampled in an anssrobic condition tnd analyged with a blood gas analyzer.
The results obtained are summarized as follows.
1. The contraction forces, maximal contraction dT/dt, maximal relaxation dT/dt were reduced markedly by methylmethacrylate monomer.
2. The latency was prolonged remarkably by methylmethacrylate monomer.
3. The heart rate was reduced markedly fr methylmethacrylate monomer.
4. The tidal volume of respiration was reduced but the respiratorr rate was increased significantly by the intravenous injection of methylmethacrylate monomer.
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