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Biomedical subjects

A H Hayes

Publications and source records attributed to A H Hayes.

At least 55 records · Page 3Linked to original sources
PubMed1978

The effect of isoniazid and other drugs on the acetylation of procainamide in the intact rat.

The effects of isoniazid (INH), hydralazine, salicylazosulfapyridine, and sulfapyridine on the quantitative disposition of procainamide (PA) in the intact rat were examined. A dose-dependent inhibition of PA acetylation was observed after coadministration of PA with INH via nasogastric intubation. The 24-hr urinary excretion of N-acetylprocainamide was noted to decline in the presence of INH whereas that of the unchanged drug exhibited a coincident rise. A reduction in the systemic clearance of PA and a prolongation in its half-life of elimination was also observed. INH increased PA hepatic levels and decreased N-acetylprocainamide hepatic content. In contrast hydralazine affects not only PA acetylation but also its absorption rate and transformation by other metabolic pathways. Salicylazosulfapyridine did not affect PA acetylation whereas high doses of sulfaphridine did.

Acetylation↗
PubMed1977

Studies on the uptake and binding of propranolol by rat tissues.

The tissue distribution of propranolol after i.v. administration (1.5 and 7.5 mg/kg) was studied in rats. Lung, brain and kidney showed extensive propranolol tissue binding. Propranolol uptake by lung seemed to be a saturable process. In contrast to the above tissues, liver propranolol concentrations remained low over the time period of study. An increase in the propranolol T1/2 was noted at the high dose and seemed to result from reduced systemic clearance and an increase in the apparent volume of distribution. Microsomal and mitochondrial fractions from several tissues contained substantial amounts of propranolol after i.v. administration and in vitro incubation with homogenates. Cytosol proteins did not bind significant amounts of propranolol. Equilibrium dialysis studies with rat liver mitochondrial and microsomal fractions revealed both high affinity, low capacity propranolol binding sites and low affinity, high capacity sites. At low concentrations, propranolol interaction with rat liver microsomes produced a type I difference spectrum with high affinity binding of similar magnitude to that observed with equilibrium dialysis. Higher concentrations of propranolol produced a saturable shift in the difference spectra with reduced binding affinity for propranolol. Results from these studies indicate that particulate fractions from several tissues contribute to the extensive tissue binding of propranolol.

Animals↗
PubMed1976

Plasma and urinary aldosterone measurement in healthy subjects with a radioimmunoassay kit not requiring chromatography.

We examined the application of a radioimmunoassay kit, not requiring chromatography, to the measurement of aldosterone in healthy human subjects. Plasma aldosterone, urinary aldosterone, and plasma renin activity measurements were performed on samples from 47 subjects under conditions in which dietary sodium intake, posture, and times of sample collection were rigidly controlled. Nomograms are presented to illustrate the continuous, rather well defined, inverse relationship between 24 h sodium excretion and aldosterone measurements in plasma and urine. Mean plasma and urinary aldosterone values for subjects on normal sodium diets were 0.332+/-0.211 nmol/liter and 36.6+/-18.6 nmol/24 h and agreed well with previously reported values. A significant (p less than 0.05 increase in 24 h urinary aldosterone, plasma aldosterone and plasma renin activity resulted with decreased dietary sodium intake and conversely, a significant (p less than 0.05) decrease in each hormone occurred with increased dietary sodium intake. Rising from the supine to upright position resulted in a 230% increase in plasma aldosterone concentrations and a 284% increase in plasma renin activity.

Aldosterone↗
PubMed1976

Persistence of biologic activity after disappearance of propranolol from the serum.

In order to evaluate the duration of the biologic effects of propranolol after the drug was discontinued, we evaluated a variety of noninvasively determined hemodynamic parameters. Significant depression was found in the heart rate (18 per cent), cardiac output (13 per cent) (determined echocardiographically), and the triple product of blood pressure, heart rate, and systolic ejection time (16 per per cent) during administration or propranolol (200 mg. per day) to 9 normal volunteers. Significant depression of these parameters was present 12 hours after discontinuing the drug. By 12 hours, serum propranolol levels had returned 90 per cent toward their base line; however, at the same time, the heart rate and cardiac output had returned only 19.4 and 14.3 per cent toward their base-line values, and the triple product had returned 41 per cent toward its baseline. By 36 hours no biologic effect was seen. Thus if propranolol were discontinued 2 days prior to cardiac surgery, no significant biologic effect would remain to complicate the patient's postoperative course.

Adult↗
PubMed1970

Oral lignocaine.

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Anti-Arrhythmia Agents↗
PubMed1970

The effect of acetyl strophanthidin on the hearts of normal dogs.

1. The ED50 of acetyl strophanthidin for producing ventricular arrhythmias in normal dogs was 54.5 mug/kg intravenously.2. Doses up to and including those which caused ventricular tachycardia did not produce either atrial arrhythmias or significant aberration of A-V conduction.3. Although the classic digitalis-induced rate and e.c.g. waveform changes may appear after administration of acetyl strophanthidin, their presence or absence have no value in predicting the subsequent development of ventricular arrhythmias.

Animals↗