Vasoconstrictor Effects of Angiotensin II on the Pulmonary Vascular Bed: Methods

Activation of the renin-angiotensin system occurs in patients with hypoxemic cor pulmonale, with raised circulating levels of angiotensin II (ANGII) and aldosterone (ALDO).” The elevated levels of ALDO are responsible for producing renal-medi-ated sodium and water retention that manifests as edema in patients with cor pulmonale. The systemic pressor effects of ANGII are well documented, whereas there is relatively little known regarding its effects on the pulmonary circulation in humans. There is some evidence from animal studies to suggest that ANGII may act in a facilitator у fashion by sensitizing the pulmonary vascular bed to the vasoconstrictor effects of hypoxemia. The purpose of the present study was to investigate the dose-response relationship of ANGII on the pulmonary vascular bed using the noninvasive technique of Doppler ultrasound.
Subjects
Eight normotensive male volunteers (age, 24 ±3 years) were studied after they had given written informed consent to a protocol approved by the Tayside Committee for Medical Ethics. Canadian neightbor pharmacy Reading here All subjects underwent a full physical examination, 12-lead electrocardiogram, echo-Doppler examination, urea and electrolytes and full blood cell count, results of all of which were required to be normal.
Protocol
All subjects were studied at the same time in the morning (9 am). On arrival at the laboratory, subjects were placed in a supine position and they remained in this position for the duration of the study. An indwelling intravenous cannula was inserted into each antecubital fossa, one for infusion of ANGII and the other for blood sampling. Baseline measurements were made after an initial intravenous control infusion of 5 percent dextrose in order to obtain a resting basal hemodynamic state. Sequential incremental 30-min infusions of ANGII (Clinalfa, Laufelfingen, Switzerland) were then given in doses of 2 ng/kg/min, 4 ng/kg/ min, and 6 ng/kg/min. A final set of measurements were then made 30 min after stopping the 6-ng/kg/min dose of ANGII (Off), to ascertain whether parameters had returned to preinfusion baseline values.