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Biomedical subjects

F A Harrison

Publications and source records attributed to F A Harrison.

At least 55 records · Page 3Linked to original sources
PubMed1974

Studies on the metabolism of 5alpha-androst-16-en-3-one in boar tests in vivo.

1. [5alpha-(3)H]5alpha-Androst-16-en-3-one (5alpha-androstenone) was infused at a constant rate for 180min into the spermatic artery of a sexually mature boar. Samples of spermatic-venous blood were collected at 1min intervals for the first 10min of the infusion and thereafter at 15min intervals for the first hour, then at 64, 125, 155 and 172min. After infusion, the testis was removed and immediately cooled to -196 degrees C. 2. From both the testicular tissue and the spermatic-venous plasma, endogenous and (3)H-labelled androst-16-enes were isolated, characterized and quantitatively determined and their specific radioactivity was calculated. 3. The specific radioactivities of 5alpha-androstenore, 5alpha-androst-16-en-3alpha-ol and 5alpha-androst-16-en-3beta-ol (an-alpha and an-beta) in testicular tissue were different from those in the spermatic-venous plasma, suggesting that these compounds may be present in more than one compartment of the testis and differentially secreted into the spermatic-venous blood. 4. The ratios of the specific radioactivities of an-alpha and an-beta to their respective sulphate conjugates in the testicular tissue were less than the ratios of the same compounds in the spermatic-venous plasma. 5. The patterns of secretion of these labelled compounds in the spermatic-venous blood during the period of infusion were demonstrated. 6. The urine that accumulated during the infusion was analysed and found to contain (3)H-labelled an-beta, conjugated as both glucuronide and sulphate, the specific radioactivities of which were determined. Little or no androst-16-enes occurred as free steroids. 7. The presence of an-beta glucuronide in the urine is discussed.

Androstenes↗
PubMed1972

Studies on the biosynthesis in vivo and excretion of 16-unsaturated C 19 steroids in the boar.

1. In one experiment [7alpha-(3)H]pregnenolone was infused continuously for 12min into the left spermatic artery of a sexually mature boar and blood was collected during this period by continuous drainage from the spermatic vein. After infusion, the testis was removed and immediately cooled to -196 degrees C. 2. From both the testicular tissue and the spermatic venous plasma, (3)H-labelled 16-unsaturated C(19) steroids were isolated and characterized and their radiochemical purity was established. 5alpha-Androst-16-en-3alpha- and 3beta-ol occurred mainly as sulphate conjugates and to a lesser extent as free steroids. Only traces of these alcohols occurred as glucosiduronate conjugates. 5alpha-Androst-16-en-3-one was found in the free (ether-extractable) fraction. 3. The isotope concentration of each of the (3)H-labelled 16-unsaturated C(19) steroids in testicular tissue was different from that in spermatic venous plasma. 4. The ratios of tritiated 5alpha-androst-16-en-3alpha- and 3beta-ol (free steroids) to their respective sulphate conjugates in the testicular tissue were less than the ratios of the same compounds in the spermatic venous plasma. The possibility that the sulphates are partially hydrolysed by testicular sulphatases before secretion is discussed. 5. In a second experiment, a continuous close-arterial infusion of [7alpha-(3)H]pregnenolone into the left testis was performed over a 200min period and all the urine that accumulated during the infusion was collected for analysis. 6. No (3)H-labelled 16-unsaturated C(19) steroids were detected in the urine as free steroids. Only a trace of 5alpha-androst-16-en-3alpha-ol was detected conjugated as glucosiduronate, whereas the corresponding 3beta-alcohol occurred mainly as glucosiduronate and to a lesser extent as sulphate. 7. The absence of 5alpha-androst-16-en-3beta-ol glucosiduronate in the spermatic venous blood and its presence in considerable amount in the urine may be attributed to hepatic glucuronyl transferase activity.

Androgens↗
PubMed1972

Ion transport across an isolated preparation of sheep rumen epithelium.

1. The fluxes of isotopically labelled sodium, potassium and chloride passing in each direction across isolated sheets of rumen epithelium from the sheep have been measured under short-circuit conditions.2. With both sides of the epithelium bathed in chloride Ringer the mean sodium fluxes were 2.85 mumole/cm(2).hr from rumen to blood and 1.28 mumole/cm(2).hr in the reverse direction. In sulphate Ringer the sodium fluxes were 1.64 mumole/cm(2).hr from rumen to blood and 0.54 mumole/cm(2).hr from blood to rumen.3. In chloride Ringer the mean potassium fluxes were 0.18 mumole/cm(2).hr from rumen to blood and 0.54 mumole/cm(2).hr from blood to rumen. In sulphate Ringer the potassium fluxes were 0.07 mumole/cm(2).hr from rumen to blood and 0.35 mumole/cm(2).hr from blood to rumen.4. In chloride Ringer the mean chloride fluxes were 4.89 mumole/cm(2).hr from rumen to blood and 3.78 mumole/cm(2).hr from blood to rumen.5. In chloride Ringer the mean value of the short-circuit current was 13 muA/cm(2), corresponding to a flux of 0.49 muequiv/cm(2).hr. When sulphate was substituted for chloride, the short-circuit current was increased by about 40%, and the net flux of sodium from rumen to blood fell by 30%.6. Neither the sodium nor the chloride fluxes changed significantly when the epithelium was temporarily open-circuited.

Animals↗
PubMed1972

Adsorption of palmitic, stearic and oleic acids in the sheep in the presence or absence of bile and-or pancreatic juice.

1. The absorption of (3)H- and (14)C-labelled palmitic, stearic and oleic acids under control conditions and in the absence of bile and/or pancreatic juice has been studied in sheep prepared with intestinal cannulae and reentrant fistulation of the thoracic lymph duct.2. Under control conditions the percentage recoveries in thoracic duct lymph of fatty acids introduced into the duodenum were: stearic acid 59.6 +/- 3.2 (mean +/- S.E. of mean), palmitic acid 71.1 +/- 1.2 and oleic acid 80.4 +/- 1.9.3. At the peak of absorption over 90% of the radioactivity was located in the triglyceride fraction.4. It was calculated that between 1900 and 3800 ml. lymph containing up to 20 g lipid flowed daily from the thoracic duct. The major fatty acids of lymph triglycerides were C(16:0) (26%), C(18:0) (39%) and C(18:1) (19%).5. In the absence of pancreatic juice, but in the presence of bile, the absorption of stearic, palmitic and oleic acids was 0.8, 4.-8.5 and 26% respectively of the dose injected into the duodenum. In the absence of bile but presence of pancreatic juice corresponding values were 0.1-0.5, 1.8 and 7.7%.6. In the absence of pancreatic juice the total lipid content of thoracic duct lymph fell from 800 to 80 mg% within 4 hr. When bile was also absent the lipid content of lymph fell further to 50 mg%.7. It is concluded that pancreatic juice functions in the lumen of the intestine probably through the production from biliary lecithin of the lysolecithin necessary for the optimum absorption of lipids.

Animals↗