OBJECTIVES We sought to use positron emission tomography (PET) to test the hypothesis that hyperhomocysteinemia adversely effects coronary microvascular dilator function. BACKGROUND Hyperhomocysteinemia is associated with abnormal endothelium-dependent vasodilation in peripheral human arteries. However, its effect on the coronary circulation is not known. METHODS Eighteen healthy humans, ag...

Background—Coronary abnormalities after Kawasaki disease (KD) may be associated with endothelial dysfunction due to intimal hypertrophy. The purpose of this study was to evaluate myocardial flow reserve (MFR) and endothelial function in regressed aneurysmal regions after KD. Methods and Results—Subjects were 12 patients aged 16.0 2.6 years who suffered from KD at 1.7 1.5 years and 12 normal sub...

Stulak, John M., Luis A. Juncos, John A. Haas, and J. Carlos Romero. Systemic hemodynamics and renal function in hemorrhaged dogs resuscitated with cross-linked hemoglobin. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 278: R28–R33, 2000.—Cross-linked hemoglobin (XL-Hb) infused into dogs increases mean arterial pressure (MAP) but decreases blood flow to the renal (RBF), mesenteric (MBF)...

Introduction Type 2 Diabetes Mellitus (T2DM) is associated with an increased risk of heart failure independently of underlying coronary artery disease (CAD) [1]. Myocardial blood flow (MBF) and MBF reserve can be abnormal in patients with T2DM due to myocardial microvascular dysfunction, contributing to the development of heart failure [2]. The myocardial layers may be affected differently by t...

Previous studies in isolated muscle preparations have shown that muscle blood flow becomes compromised at higher contraction frequencies. The purpose of this study was to examine the effect of increases in contraction frequency and muscle tension on mean blood flow (MBF) during voluntary exercise in humans. Nine male subjects [23.6 +/- 3.7 (SD) yr] performed incremental knee extension exercise ...

BACKGROUND The impact of time-of-flight (TOF) in myocardial perfusion (13)N-ammonia positron emission tomography (PET) is unclear. METHODS AND RESULTS Twenty consecutive subjects underwent rest and adenosine stress (13)N-ammonia myocardial perfusion PET. Two sets of images were reconstructed using TOF-ordered subset expectation maximization (TOF-OSEM) and 3-dimensional row-action maximum like...

We tested the hypothesis that activation of angiotensin type 2 (AT(2)) receptors, by both exogenous and endogenous ANG II, modulates neurally mediated vasoconstriction in the renal cortical and medullary circulations. Under control conditions in pentobarbital-anesthetized rabbits, electrical stimulation of the renal nerves (RNS; 0.5-8 Hz) reduced renal blood flow (RBF; -88 +/- 3% at 8 Hz) and c...

The effect of coronary artery bypass grafting (CABG) on absolute myocardial blood flow (MBF) has not been investigated previously. MBF (ml. min(-1). g(-1)) was measured at rest and during hyperemia (0.56 mg/kg iv dipyridamole) using H(2)(15)O and positron emission tomography in eight patients with three-vessel disease before surgery and 1 and 6 mo after full revascularization. Baseline MBF was ...

In vivo observations of microcirculatory behavior during autoregulation and adaptation to varying myocardial oxygen demand are scarce in the human coronary system. This study assessed microvascular reactions to controlled metabolic and pressure provocation [bicycle exercise and external counterpulsation (ECP)]. In 20 healthy subjects, quantitative myocardial contrast echocardiography and arteri...

Methods Twenty-four healthy volunteers (12 men, 12 women) underwent MRI in a 3 Tesla scanner (Verio, Siemens, Erlangen, Germany). CPT was performed by immersing the right ankle in ice-water during 4 min. Heart rate and blood pressure were monitored throught the protocol. Coronary sinus flow was measured at rest and during CPT using a non breath-hold velocity encoded phase contrast cine MRI (TR/...