lanatoside-c and Hypertension

To investigate whether the impaired reflex response to cardiopulmonary baroreceptor unloading in hypertensive patients with left ventricular hypertrophy can be promptly improved by a pharmacological challenge. For this purpose we studied the effects of acute digitalis administration on cardiopulmonary baroreflex, evaluated by forearm noradrenaline spillover.. Eleven hypertensives with left ventricular hypertrophy and 10 age- and sex-matched normotensives underwent the application of -5 and -10 mmHg lower-body negative pressure (LBNP) before and after the administration of digitalis. Forearm noradrenaline spillover, measured using a tracer technique, was used to estimate the reflex sympathetic response.. Under control conditions LBNP evoked a similar fall in right atrial pressure in the two study groups. In the normotensives there was a significant increase in forearm noradrenaline spillover. In the hypertensives no significant changes in forearm noradrenaline spillover were found. Intravenous administration of 0.02 mg/kg lanatoside C was associated with an increase in systolic blood pressure and a reduction in forearm noradrenaline spillover in both groups. In the normotensives the percentage change in forearm noradrenaline spillover induced by LBNP increased significantly in response to digitalis administration. However, digitalis restored the response of forearm noradrenaline spillover to LBNP in the hypertensives, so that no significant difference in this response was detected between the two study groups. Digitalis did not modify the effects of LBNP on cardiac pressures in either group.. The present results demonstrate that administration of lanatoside C restores the response of forearm noradrenaline spillover to cardiopulmonary baroreceptor unloading in hypertensive patients with left ventricular hypertrophy. This indicates that the impairment of cardiopulmonary baroreflexes in these patients can be reversed by acute pharmacological treatment. Therefore, impairment of this reflex response seems to be related to functional rather than to structural abnormalities of the hypertrophied ventricle.

Topics: Digitalis Glycosides; Female; Forearm; Hemodynamics; Humans; Hypertension; Hypertrophy, Left Ventricular; Lanatosides; Male; Middle Aged; Norepinephrine; Pressoreceptors; Reflex; Sympathetic Nervous System

Several studies in animals and in man have suggested that the inhibitory influence of baroreceptors on heart rate and peripheral circulation is enhanced by digitalis. Because the atrio-ventricular node represents a key site for the clinical action of digitalis we studied how baroreceptor control of atrio-ventricular conduction is modified by digitalis at therapeutical doses. In eight subjects heart rate was kept constant by atrial pacing to assess neural influences on atrio-ventricular conduction rate without the modifications caused by simultaneous changes in cardiac cycle length. Arterial baroreceptors were stimulated by increasing or reducing blood pressure (intra-arterial recording), via an iv bolus of phenylephrine or nitroglycerine. The baroreflex sensitivity was assessed in ms . mmHg-1 as the slope of the linear regressions relating the rise or fall in systolic blood pressure to the lengthening or shortening in St- (atrial stimulus artifact) Q interval (ECG recording). The study was performed before and 45 min after iv administration of digitalis (0.8 mg of Lanatoside C). Baroreflex sensitivity during baroreceptor stimulation was 2.9 +/- 1.1 ms . mmHg-1 (mean +/- SE) before digitalis, whereas after digitalis a significantly and markedly greater value of 5.6 +/- 1.5 ms . mmHg-1 was found. Baroreflex sensitivity during baroreceptor deactivation was 0.9 +/- 0.1 ms . mmHg-1 before digitalis, and was not significantly affected by the drug. Thus in man the baroreceptor control of atrio-ventricular conduction is strikingly potentiated by digitalis although this potentiation is only evident in the upper portion of the stimulus-response curve of the reflex.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Atrioventricular Node; Blood Pressure; Female; Heart Conduction System; Humans; Hypertension; Lanatosides; Male; Nitroglycerin; Phenylephrine; Pressoreceptors; Reflex; Sinoatrial Node

Topics: Administration, Oral; Adult; Aged; Coronary Disease; Female; Heart Defects, Congenital; Heart Diseases; Humans; Hypertension; Lanatosides; Male; Middle Aged; Pulmonary Heart Disease; Rheumatic Heart Disease; Time Factors

Topics: Aortic Valve Stenosis; Arrhythmias, Cardiac; Coronary Disease; Deslanoside; Humans; Hypertension; Lanatosides; Mitral Valve Insufficiency; Mitral Valve Stenosis

Topics: Cardiac Catheterization; Humans; Hypertension; Hypertension, Pulmonary; Lanatosides; Mitral Valve Insufficiency; Mitral Valve Stenosis; Pharmacology; Pneumonectomy; Pulmonary Circulation; Pulmonary Emphysema

Topics: Adolescent; Angina Pectoris; Arrhythmias, Cardiac; Atrial Fibrillation; Child; Coronary Disease; Deslanoside; Geriatrics; Heart Block; Heart Failure; Humans; Hypertension; Lanatosides; Myocardial Infarction; Pharmacology; Pulmonary Edema; Pulmonary Fibrosis; Pulmonary Heart Disease; Tachycardia; Thrombophlebitis; Toxicology; Water-Electrolyte Balance

Topics: Digitalis; Digitalis Glycosides; Guinea Pigs; Hypertension; Lanatosides