Electron transfer mechanism of aromatic 'nucleophilic' substitution

Mechanistic implications of the ready formation of aryl iodides from aryldiazonium salt solutions and the iodide ion (in contrast with the general need for cuprous or other catalysts with other halides) have been studied. The reaction between benzenediazonium fluoroborate and potassium iodide in methanol at 0�C has been investigated. A new mechanism involving initial one-electron transfer from the iodide anion to the benzenediazonium cation, resulting in the formation of radical intermediates by heterolytic cleavage of a bond, has been proposed in order to account for the products, viz. iodobenzene, benzene, biphenyl, iodine, anisole, and formaldehyde, and the effect of photochemical catalysis.

Experimental myocardial infarction. X. Efficacy of glucagon in acute and healing phase in intact conscious dogs: effects on hemodynamics and myocardial oxygen consumption

This study was designed to test the efficacy of glucagon in the treatment of hemodynamic abnormalities of acute and healing experimental canine myocardial infarction. Myocardial infarction was produced in intact, conscious dogs by gradual inflation of a balloon cuff device implanted around the left anterior descending coronary artery 1 to 2 weeks prior to the study. Hemodynamic and metabolic effects of 50 µg/kg of glucagon were assessed serially in the control state, 1 hour after myocardial infarction and again 1 week later. In the control state glucagon improved cardiac performance and increased myocardial oxygen consumption. One hour after acute myocardial infarction glucagon improved cardiac performance and reduced the degree of left ventricular failure, without any increase in myocardial oxygen consumption. Similar effects of glucagon were noted in the healing phase of myocardial infarction. It is postulated that in this animal model in the presence of heart failure due to myocardial infarction there are reciprocal changes in the factors that increase myocardial oxygen consumption (glucagon-induced inotropy) and decrease oxygen consumption (fall in ventricular end-diastolic volume and wall stress), resulting in no net change in oxygen requirement.