Effects of magnesium sulphate on the cardiovascular system, coronary circulation and myocardial metabolism in anaesthetized dogs

Abstract

We have studied the effects of i.v. bolus doses of magnesium sulphate (MgSO4) 60, 90 and 120 mg kg-1 on haemodynamic state, the coronary circulation and myocardial metabolism in nine dogs anaesthetized with pentobarbitone and fentanyl. MgSO4 produced dose-dependent decreases in arterial pressure, heart rate, left ventricular dP/dtmax and left ventricular minute work index (LVMWI) and an increase in the time constant of left ventricular isovolumic relaxation. Stroke volume increased, systemic vascular resistance decreased and cardiac output did not change significantly. MgSO4 produced decreases in coronary perfusion pressure, coronary vascular resistance and myocardial oxygen consumption (MVO2). Coronary sinus blood flow, lactate extraction ratio and the ratio of LVMWI to myocardial MVO2, that is an index of cardiac efficiency, did not change significantly. This study indicated that the depressant effect of MgSO4 on cardiac function was offset by lowering of peripheral vascular resistance, so that cardiac pump function remained effective, and the almost constant coronary sinus blood flow resulted from the decrease in coronary vascular resistance even at higher doses.

Effects of three divalent cations: manganese, zinc, and magnesium on arterial blood pressures in guinea pigs

“…, 10 )4 mol/kg IV, respectively) every 25 min and observed that the systolic, diastolic, and mean arterial blood pressures were decreased after each dose. Some authors [17,26] reported that heart rate was increased dose-dependently with intravenously MgSO 4 , whereas others have reported a decrease [18,27] or no change [20À25]. In our experiments, heart rate was not changed by MgSO 4 .…”

“…Numerous epidemiological and clinical studies have suggested an inverse relationship between dietary intake of magnesium and blood pressure, implying that insufficient magnesium intake is associated with an increased risk for hypertension [15,16]. Nakayama [17] and Nakaigawa et al [18] reported that arterial blood pressures decreased in dogs with increasing doses of Mg…”

The Effect of Intravenous Magnesium Sulfate and Lidocaine in Hemodynamic Responses to Endotracheal Intubation in Elective Coronary Artery Bypass Grafting: a Randomized Controlled Clinical Trial

“…MGS was chosen since it is a vasodilator with minimal myocardial depression (16) which is the dose-dependent depressant effect on cardiac contractility. It has been shown that the depressant effect of MGS on cardiac function is offset by lowering the systemic vascular resistance (SVR) and hence, MGS maintains cardiac pump function (17). We know that MAP is determined by cardiac output (CO), SVR, and central venous pressure (CVP) according to the following equation, which is based on the association among flow, pressure, and resistance: MAP = (CO × SVR) + CVP; CVP is usually at or near 0 mmHg; therefore, this formula is often simplified to: MAP ~ CO × SVR.…”

Hyperkalemic cardioplegia for adult and pediatric surgery: end of an era?

“…Magnesium is often added to cardioplegia to reduce intracellular Ca 2+ loading during ischemia (Nakaigawa et al, 1997; Ichiba et al, 1998; Murphy, 2000; Mubagwa et al, 2007) and to counter K + -induced vasoconstriction (Matsuda et al, 1999; Yang and He, 2005). Colder temperatures also offset the vasoconstriction effects of high potassium (Chiavarelli et al, 1982), however, it can lead to local and systemic inflammation, coagulation disturbances and tissue edema (Mezzetti et al, 1995; Torracca et al, 1996; Gaillard et al, 2000; Torchiana et al, 2000; Ravishankar et al, 2003).…”