Ten patients with chronic obstructive pulmonary disease without complicating cor pulmonale were studied by right and left heart catheterization. Respiratory and haemodynamic observations were made during a control period and during the infusion of phentolamine. Phentolamine produced a significant reduction in mean pulmonary artery pressure from I8 8 mmHg to I3 I mmHg, right ventricular end-dias...

The effects of the commonly employed systemic vasodilators phentolamine, nitroprusside, and intravenous glyceryl trinitrate on cardiac performance, peripheral resistance, and vascular capacitance, as judged by changes in left ventricular filling pressure, were compared in 29 patients studied within 24 hours after the onset of acute myocardial infarction. To provide a common basis for comparison...

Maintained reduction in extracellular K+ concentrations [( K]e) of isolated canine mesenteric arteries produced two contractions separated by a period of several hours. The mechanisms for respective early and late contractions were investigated. First, early responses to reduced [K]e were examined quantitatively over a period of 2 hr. Critical [K]e for initiating the contraction was 0.14 mM. Ea...

BACKGROUND AND OBJECTIVES There is evidence that the passage of nociceptive information through the posterior horn of the spinal cord (PHSC) on its way to rostral levels of the central nervous system undergoes profound excitatory and inhibitory influences. The objective of the present study was to compare the effects of the subarachnoid administration of methysergide, phentolamine, and phentola...

=Abstract=The effects of dopamine on gastric motility were investigated using circular muscle strips prepared from the antral and' fundic regions of the guinea-pig stomachs. The spontaneous and phasic contractions induced by electrical stimulation were recorded with a force transducer. Dopamine potentiated the spontaneous contraction of the antral circular muscle, which was suppressed completel...

Animal studies indicate alpha-adrenergic coronary vasoconstriction helps maintain left ventricular function during physiological stress. Whether this process occurs in humans is unknown. In the current study, we used transthoracic Doppler echocardiography to test the effect of lower body negative pressure (LBNP) on coronary blood flow velocity (CBV, left anterior descending coronary artery) and...

Normal adult men and women have been infused with epinephrine, 6 mug per minute, during lipolytic blockade with nicotinic acid, beta-adrenergic blockade with propranolol and Butoxamine, and alpha-adrenergic blockade with phentolamine. Epinephrine infusion was associated with low serum levels of immunoreactive insulin (IRI) except when phentolamine was given simultaneously. These findings are co...

The role of the sympathetic nervous system in the renal vasoconstriction induced by sodium restriction has been assessed in normal man in balance on a 10-mEq sodium intake. Renal blood flow was measured with radioxenon injected into the renal artery. Phentolamine infused into the renal artery at rates of up to 3 mg/min did not increase net renal perfusion or alter its intrarenal pattern. That d...

Large doses of the imidazoline alpha 2 adrenoreceptor agonist clonidine aggravate ethanol-induced gastric lesions. The alpha 2 adrenoceptor antagonist phentolamine, the opioid antagonist naloxone and the H2 antagonist cimetidine do not prevent this action of clonidine suggesting that it is not mediated by alpha 2, opioid or H2 receptors. Further, like clonidine, high doses of phentolamine and c...

BACKGROUND Maximal hyperaemia is paramount in the diagnosis of patients with coronary artery disease. However in these patients, enhanced alpha-adrenergic microvascular vasoconstriction may preclude adenosine to induce maximal hyperaemia. AIM To assess the presence and the clinical relevance of residual microvascular resistance after administration of adenosine. METHODS AND RESULTS Fraction...