Efeitos do propofol na resposta contrátil do miocárdio à dopamina e dobutamina: estudo experimental em corações isolados de ratos

Análise comparativa dos efeitos do diazepam, midazolam, propofol e etomidato na contratilidade miocárdica e no fluxo coronariano: estudo em corações isolados de ratos

“…Thus the concentration is within the range currently used in clinical practice which is between 5 and 32 mcg/mL [19]. The results we obtained with the use of diazepam confirmed the conclusions of CHAI & WANG [1] in 1966, DANIELL [4] in 1975, GONZALES et al [5] in 1990, MEDEIROS et al [8] in 1995 and PONTES [9] in 1994. However our results differ from those of PRINDLE et al [2] and ABEL et al [3] in 1970, who demonstrated an innocuous action or even a positive inotropic action after the use of the drug.…”

“…Taking into account the mean coronary blood flow of 7.2 mL/min at the moment of injection of the drug, the employed dose corresponds to 3.74 mcg/mL of midazolam, thus less than the plasma concentration determined by the dose of 0.3 mg/kg which is currently used in anesthesia (0.4 to 2.0 mg/kg) [19]. The data reported here confirm the results obtained by REVES et al [20] in 1984, MEDEIROS et al [8] in 1995 and PONTES [9] in 1994, who described myocardial depressant effects caused by the use of midazolam. These results did not agree, on the other hand with those published by MARTY & NITENBERG [6] in 1990, who did not evidence a depressant action in the myocardium that justified the hypertensive effect observed after the use of midazolam.…”

“…The marked alterations occur with the two doses (25 mcg and 50 mcg) that, when considering the coronary blood flow at the moment of injection as previously mentioned, determined concentrations of 2.57 mcg/mL and 9.09 mcg/mL, much lower than those (24 to 30 mcg/mL) obtained with the use of doses currently employed in clinical practice (1.6 to 2.5 mg/kg) [19]. These results confirm those published by BRÜSSEL et al [10] in 1989, PUTTICK et al [21] in 1992, MEDEIROS et al [8] in 1995 and PONTES [9] in 1994, who reported depressant effects on the myocardium with the use of propofol. On the other hand, the results differ from those presented by GOODCHILD & SERRAO [11] in 1989 and MOUREN et al [12] in 1994, who did not evidence significant alterations in the myocardial contractility, or did not evidence contractile depression that justified the adverse effects observed in the arterial blood pressure after the injection of the drug.…”

“…MARTY & NITENBERG [6], in the same year, contested that myocardial depression determined by midazolam could cause the hypotensor effect observed after its use, rekindling an old controversy about the action of the benzodiazepinic agents on the myocardial contractility. HERNÀNDEZ [7], in 1991, MEDEIROS et al [8], in 1995 and PONTES [9], in 1994, demonstrated using isolated rat hearts, inhibition of the myocardial contractility after the infusion of diazepam, midazolam and propofol, reaffirming previously reported concepts.…”

<![CDATA[<b>Effects of diazepam, midazolam, propofol and etomidate in myocardial contractility and coronary blood flow</b>: <b>comparative analysis in isolated rat's hearts</b>]]>

“…HERNÀNDEZ [7], in 1991, MEDEIROS et al [8], in 1995 and PONTES [9], in 1994, demonstrated using isolated rat hearts, inhibition of the myocardial contractility after the infusion of diazepam, midazolam and propofol, reaffirming previously reported concepts.…”