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Biomedical subjects

M G White

Publications and source records attributed to M G White.

At least 55 records · Page 3Linked to original sources
PubMed1972

Relationship of sodium reabsorption and glomerular filtration rate to renal glucose reabsorption.

Glucose reabsorption was measured in dogs in which sodium reabsorption was stimulated by obstruction of the thoracic inferior vena cava or inhibited by volume expansion with Ringer's lactate. Glucose reabsorption was much higher during periods of enhanced sodium reabsorption than during sodium diuresis. The relationship of glucose reabsorption to glomerular filtration rate was examined using data from animals that had fractional sodium excretion rates of less than 1%. Under this condition the relationship of glucose reabsorption to glomerular filtration rate is highly linear. When points obtained during sodium diuresis (C(Na)/GFR>0.1) are plotted on the same graph, glucose reabsorption at any given glomerular filtration rate is much less than during antidiuresis. Glucose reabsorption divided by glomerular filtration rate varies inversely with fractional sodium excretion. This study demonstrates that glomerular tubular balance for glucose exists in the dog and that this balance is changed when sodium reabsorption changes.

Animals↗
PubMedDate not supplied

The effect of intravenous bumetanide in man with normal and low renal function.

Bumetanide was administered intravenously to four groups of patients with varying levels of glomerular filtration rate (average 10 to 108 ml/min/1.73 m2 B.S.A.). The dose of bumetanide was either 0.25, 0.5, 1.0, or 2.0 mg administered by intravenous "push." The intravenous administration produced a prompt and marked increase in sodium, chloride, and calcium excretion. The effect was brief, lasting 30 to 60 minutes, but persisted to some extent with the 2.0 mg dose beyond 120 minutes. There was no effect on phosphate excretion or on the parameters of net acid excretion.

Adolescent↗
PubMedDate not supplied

The effect of loop diuretics on the excretion of Na+, Ca2+, Mg2+, and Cl-.

Bumetanide, ethacrynic acid, and furosemide were administered in two equipotent doses to the same five dogs in three separate studies. Intravascular volume was maintained by the replacement of urinary losses. Fractional chloride excretion was used as a marker of diuretic effect. Comparison of absolute and fractional excretion of Na+, Cl-, Ca2+, and Mg2+ did not demonstrate a significant difference among the three diuretics.

Animals↗
PubMedDate not supplied

Transcatheter vascular occlusion of the small patent ductus arteriosus: an alternative method.

The current strategies concerning a small (</=2 mm) patent ductus arteriosus (PDA) include surgical ligation, transcatheter implantation of the Rashkind occluder device, or no intervention requiring indefinite endocarditis precautions. Five patients have undergone successful transcatheter closure of a small-caliber PDA utilizing a single 3 mm Gianturco occluder coil as an alternative to surgical ligation. The coil was delivered to traverse the narrowest dimension of the PDA, leaving loops of coil in both the pulmonary and aortic ends of the ductus. All PDAs were successfully occluded, and the duration of hospitalization for all patients was 1 day. At latest follow-up (11 +/- 2 months), echocardiography demonstrates complete ductus occlusion in all patients, with no obstruction to left pulmonary arterial or descending aortic flow. Transcatheter coil occlusion of the small ductus is an easily accomplished, safe, effective alternative to surgical ligation, thereby avoiding a lateral thoracotomy incision, shortening hospitalization, and reducing costs.

Aorta, Thoracic↗
PubMedDate not supplied

Autonomic nervous control of heart rate orienting and alpha responses in dog.

The object of this experiment is to study the autonomic nervous control of alpha responses elicited in classical conditioning. Twenty-two mongrel dogs were trained in classical discriminative conditioning. Typical two-phase tachycardic responses were observed in positive (CS+) trials while only the earliest, phase 1, response was observed in negative (CS-) trials. The phase 1 response, which was identical in CS+ and CS-trials, was compared in dogs before and after selective SA-nodal parasympathectomy (N = 7) and beta-adrenergic blockade (N = 11). The phase 1 tachycardic response was eliminated by selective SA-nodal parasympathectomy but not by beta-adrenergic blockade. We conclude that the phase 1 response observed in both CS+ and CS-trials with similar time sequence and magnitude is an alpha response. The heart rate orienting response results from a withdrawal of parasympathetic activity with little or no change in sympathetic tone.

Animals↗