Bollman, Jesse L.

This study was undertaken to determine the site of maximal absorption of Co60-labeled vitamin B12 in the small intestine of the male albino rat. Animals were sacrificed at intervals after ingestion of the labeled vitamin. The highest concentration of radioactivity was found in the wall of the upper and mid-ileum 1/2–3 hours after ingestion. Accordingly, the absorption of tagged vitamin B12 was estimated by fecal and urinary excretion methods in animals with resections of portions of the small intestine, including the portion containing the ileocecal valve, and in normal controls. Resection of the middle half of the small bowel (the upper and mid-ileum) was found to produce significant impairment of vitamin B12 absorption. It is concluded that in the male albino rat the upper and mid-ileum is specifically adapted to most efficient absorption of vitamin B12.

Dogs with biliary fistulas metabolized triiodothyronine rapidly to inorganic iodide, as did normal dogs. The amount and distribution of I131 compounds in the urine were not greatly altered by withdrawal of the bile, which contained about one-fourth of the I131 administered. Dogs with biliary obstruction excreted more of compounds b, iodide and the conjugate than normal dogs. The absence of enterohepatic circulation of metabolic products of triiodothyronine usually excreted in the bile did not appreciably alter the products or rate of metabolism of triiodothyronine. Some of the same products of triiodothyronine appeared in both bile and urine but there was very little inorganic iodide in the bile and much more of the glucuronide and the water-soluble, column residual fraction.

A fluorometric method was used to quantitate plasma epinephrine and norepinephrine during hemorrhagic and anaphylactic shock in healthy adult dogs anesthetized with pentobarbital. Arterial plasma was analyzed before and after hemorrhage in four dogs. Loss of approximately 18% of blood volume through rapid arterial bleeding caused no remarkable change in pressor amines. Loss of approximately one-third of the total blood volume decreased the mean arterial pressure by a range of 56–81% and invariably caused increased concentration of plasma pressor amines. The average concentration of epinephrine increased from 1.0 to 7.8 µg/1. of plasma, and that of norepinephrine increased from 2.5 to 3.6 µg. Additional bleeding caused further increase of plasma pressor amines. Seven dogs were given egg white intravenously to sensitize them. Subsequently, whenever a severe reaction (hypotension, bradycardia and respiratory depression) resulted from intravenous administration of egg white, venous plasma pressor amines increased. The average concentration of epinephrine increased from 0.7 to 7.7 µg/1. of plasma; norepinephrine increased in three dogs but remained unchanged or decreased in the remaining animals. Without a preceding ‘shock’ reaction, change in concentration of epinephrine-like substance was unremarkable. Intravenous administration of 1 mg of histamine base produced hypotension and usually slight increase of plasma pressor amines.