Francis J. Haddy

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Unlike sodium, potassium is vasoactive; for example, when infused into the arterial supply of a vascular bed, blood flow increases. The vasodilation results from hyperpolarization of the vascular smooth muscle cell subsequent to potassium stimulation by the ion of the electrogenic Na+-K+ pump and/or activating the inwardly rectifying Kir channels. In the(More)
Hemodynamic and metabolic characteristics of an isolated guinea pig heart preparation perfused with a pyruvate fortified Krebs-Ringer-bicarbonate solution are described. The preparation is stable for more than 90 min with respect to coronary flow, heart rate, left ventricular pressure,dP/dt, oxygen consumption, and myocardial high energy phosphate levels.(More)
In an attempt to test the hypothesis whether adenosine is involved in the regulation of coronary flow, adenosine, inosine and hypoxanthine were measured in the effluent perfusate and in the tissue of isolated guinea pig hearts under various experimental conditions. In addition, the release of14C-adenosine,14C-inosine and14C-hypoxanthine was determined after(More)
Coronary dilation induced by infusion of adenosine, adenine nucleotides, dipyridamole, and papaverine was quantitated in the spontaneously beating isolated perfused guinea pig heart. Theophylline antagonized the effects of all the substances tested. The inhibition proved to be reversible and of a competitive type. Single injections of ADP and ATP induced(More)
A local increase in the extracellular potassium concentration [K+]o, up to about 8 meq/liter either by topical application or intra-arterial infusion of K+ salts, causes arteriolar dilation and decreased resistance to blood flow in systemic vascular beds. Isolated vascular smooth muscle responds to a similar increase in [K+] in the bathing fluid with(More)
Periventricular forebrain regions participate in body fluid and cardiovascular regulatory mechanisms that are intimately related to neural participation in experimental hypertension. Ablation of preoptic-hypothalamic periventricular tissue surrounding the anteroventral third ventricle (AV3V) disrupts both angiotensin (AngII) and sodium regulatory mechanisms(More)
In two series of experiments we studied the effects of indomethacin on (a) coronary reactive hyperemia and, (b) renal blood flow, autoregulation, and reactive dilation. Coronary blood flow was measured in closed-chest dogs. Reactive hyperemia was induced by coronary occlusion for 5 and 15 sec. Indomethacin, an inhibitor of prostaglandin synthesis, was(More)
GAZITGA, S., J. B. SCOTT, B. SWINDALL, AND F. J. HADDY. Resistance responses to local changes in plasma osmolality in three vascular beds. Am. J. Physiol. 220(Z) : 384-391. 1971 .-The effects of local changes in plasma osmolality (durations of 3-10 min) on resistance to blood flow were compared in the forelimb, renal, and coronary circulations of(More)