Inductive displacement gauge.

Strain gauges are often used for the measurement of contractile activity of muscle tissue. In these cases the strain gauge is used as a force measuring device. Because of its stiffness, the strain-gauge-type transducer resists changes in length produced by contraction, and this could cause secondary effects. This paper describes an alternative method to evaluate contractions. Displacement rather than force is measured. The device offers very little resistance to motion and thus does not constrain the tissue. The sensitivity of the transducer is very high. An additional feature is the low cost of the transducer compared to strain-gauge devices.

Electrical and mechanical activity in the ex vivo perfused total canine colon.

Electrical and mechanical activity were studied in the ex vivo total canine colon, supported in a perfusion chamber by a supporting dog. Regular electrical activity could be recognized visually in 50--70% of the records. The frequency of this activity was in the range of 7--10/min. Fourier analysis also revealed dominant frequencies in this range. Two types of mechanical activity were observed. The first consisted of small amplitude repetitive contractions, which appeared both during quiescent periods and during vigorous contractions. The frequency of this rippling, when periodic, usually approximated that of the electrical activity. The second type consisted of large amplitude prolonged (30--135 sec) contractions. Without stimulation, the large amplitude contractions were asynchronous and not propagated. Following neostigmine, however, the large amplitude contractions were always propagated aborally and were usually associated with evacuation of the colon. The rippling contractions had a frequency similar to the regular electrical activity and are probably under their control. The large amplitude, prolonged duration contractions are unlikely, however, to be solely under myogenic control.

Secretion of insulin by the canine pancreas perfused ex vivo with fluorocarbon emulsion.

Canine gastroduodenopancreatic blocks were isolated and perfused ex vivo with oxygenated bloodless fluorocarbon emulsion. Pancreatic and gastric secretions were collected. Exocrine pancreatic secretion was stimulated with secretin infused intra-arterially. This study was undertaken to find out whether or not the pancreas, perfused with fluorocarbon emulsion, preserves its endocrine function. Immunoreactive insulin was determined in the perfusate samples obtained from a venous site in the perfusion circuit. Glucose concentration was also measured in the same samples. Insulin appeared in all experiments within the first ten minutes of persuion of the preparation with fluorocarbon. Insulin was present in all samples collected during 5.5 hours of perfusion. Results of this study suggest that endocrine function of the pancreas was preserved under the conditions of extracorporeal perfusion used.

Exocrine secretion of canine pancreas perfused extracorporeally.

A canine gastroduodenopancreatic block was isolated and perfused extracorporeally with homologous blood. This preparation was used for studying stimulated exocrine secretion of the pancreas. Stimulants were infused intra-arterially. Both vagi were stimulated electrically. Hydrochloric acid or L-phenylalanine were instilled intragastrically. Pancreatic secretion induced by secretin and during HCl instillation was rich in bicarbonate and poor in total protein. Pancreatic secretion obtained during the infusion of normal saline, cholecystokinin, bethanechol chloride or acetylcholine chloride and during instillation of amino acid as well as during electrical stimulation of vagi, contained less bicarbonate and more protein than secretin-induced secretion.

Effect of somatostatin on pentagastrin stimulated secretion by isolated canine stomachs, perfused ex vivo with homologous blood.

The effect of somatostatin on pentagastrin-induced gastric secretion was assessed on 6 isolated canine stomachs perfused ex vivo with homologous blood. Hormones were given at a constant rate into the gastric arterial circulation. Somatostatin caused inhibition of the HCl concentration and output and reduced the secretion volume in all stomachs studied. The output but not the concentration of pepsin was also reduced.