AMERICAN JOURNAL OF PHYSIOLOGY Vol. 229, No. 4, October 1975. Printed
Distributions
in U.S.A.
of spike bursts
in cat duodenum
ARTURO G. SANCHOLUZ, THOMAS E. CROLEY II, JOHN R. GLOVER, EN20 0. MACAGNO AND JAMES CHRISTENSEN Iowa Institute of Hydraulic Research, Division of Energy, and Gastroenterology Research Laboratories, Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242 SANCHOLUZ, ARTURO G., THOMAS E. CROLEY II, JOHN R. GLOVER, ENZO 0. MACAGNO, AND JAMES CHRISTENSEN. Ddribu-
Closely spaced electrodes were used in the cat duodenum in vitro to estimate the dimensions and configurations of with the assumption of a high single ring contractions, correlation between the electrical spike bursts and the initiation of contraction.
tiun of spike bursts in cat duodenum. Am. J- Physiol. 229(4) : 925-929. 1975.-The histograms of spike bursts over short distances were examined in the isolated cat duodenum with multiple electrodes arranged circumferentially and longitudinally. At a single cross section of the duodenum, spike bursts occurred simultaneously in any single slow-wave cycle, but all eight monitored sites in the circumference participated simultaneously only in about 25 TO of the spike-burst cycles. There also were wide variations in the incidence of spike bursts at different locations in a planar cross section. In a longitudinal section, net level of activity over short distances varied widely. Also, spike bursts were out of phase in the longitudinal axis, appearing to spread caudad; 80 TO of spike burst groups involved less than an average of 5.5 consecutive electrode sites (spaced at 5-mm intervals). Since spike bursts seem to be correlated with ring contractions of the circular muscle, the fact that they appear sequentially in time along the duodenum indicates that such contractions must always be peristaltic. An estimated 807, of such contractions sweep less than about 3 cm. Records of spike bursts from a single electrode do not accurately reflect activity beyond that one point site. electrophysiology;
peristalsis;
gastrointestinal
MATERIALS
AND
METHODS
Sixteen cats, weighing 3.0-5.0 kg, were anesthetized by intrapleural injection of sodium pentobarbital, 40 “g/kg. In each cat, a lo-cm segment of the duodenum, beginning about 1 cm below the pylorus, was quickly excised, emptied, and mounted on a perforated Plexiglas tube, 4 mm OD, with the ends tied in place so that it lay at its approximate in situ length. This tube was then fastened to the bottom of a cylindrical Plexiglas organ bath so that the duodenum was mounted vertically in the core of the cylindrical tank. Krebs solution was recirculated continuously through the bath, entering through the lumen of the perforated tube which held the duodenum and flowing out through the bottom of the cylindrical tank. This recirculation was effected by a peristaltic finger pump acting on rubber tubing in an external circuit which included a glass heat exchanger. The jacket of the heat exchanger was perfused continuously with warmed water to maintain the Krebs solution in the organ bath at 36.5-37.5”C. The organ bath fluid was aerated continuously with 95 % 02-5 % COZ. The walls of the organ bath contained holes along both the circumference and the longitudinal axis to allow insertion of electrodes. These holes contained rubber O-ring gaskets to seal the electrodes. Silver-silver chloride glass pore electrodes (4) were inserted to touch the serosal surface of the duodenum. Electrode resistance was measured periodically during the experiments and electrodes with resistances greater than 2 k!2 were discarded in view of the input impedance of the amplifiers of 100 kS1. Records of the electrical potential difference were made separately from each electrode against a common grounded reference electrode, a coil of chlorided silver wire placed in the bottom of the cylindrical bath. In order to ascertain whether spike bursts were being satisfactorily recorded by this technique, electrodes were replaced by new ones whenever an isolated ‘
Distributions
in U.S.A.
of spike bursts
in cat duodenum
ARTURO G. SANCHOLUZ, THOMAS E. CROLEY II, JOHN R. GLOVER, EN20 0. MACAGNO AND JAMES CHRISTENSEN Iowa Institute of Hydraulic Research, Division of Energy, and Gastroenterology Research Laboratories, Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242 SANCHOLUZ, ARTURO G., THOMAS E. CROLEY II, JOHN R. GLOVER, ENZO 0. MACAGNO, AND JAMES CHRISTENSEN. Ddribu-
Closely spaced electrodes were used in the cat duodenum in vitro to estimate the dimensions and configurations of with the assumption of a high single ring contractions, correlation between the electrical spike bursts and the initiation of contraction.
tiun of spike bursts in cat duodenum. Am. J- Physiol. 229(4) : 925-929. 1975.-The histograms of spike bursts over short distances were examined in the isolated cat duodenum with multiple electrodes arranged circumferentially and longitudinally. At a single cross section of the duodenum, spike bursts occurred simultaneously in any single slow-wave cycle, but all eight monitored sites in the circumference participated simultaneously only in about 25 TO of the spike-burst cycles. There also were wide variations in the incidence of spike bursts at different locations in a planar cross section. In a longitudinal section, net level of activity over short distances varied widely. Also, spike bursts were out of phase in the longitudinal axis, appearing to spread caudad; 80 TO of spike burst groups involved less than an average of 5.5 consecutive electrode sites (spaced at 5-mm intervals). Since spike bursts seem to be correlated with ring contractions of the circular muscle, the fact that they appear sequentially in time along the duodenum indicates that such contractions must always be peristaltic. An estimated 807, of such contractions sweep less than about 3 cm. Records of spike bursts from a single electrode do not accurately reflect activity beyond that one point site. electrophysiology;
peristalsis;
gastrointestinal
MATERIALS
AND
METHODS
Sixteen cats, weighing 3.0-5.0 kg, were anesthetized by intrapleural injection of sodium pentobarbital, 40 “g/kg. In each cat, a lo-cm segment of the duodenum, beginning about 1 cm below the pylorus, was quickly excised, emptied, and mounted on a perforated Plexiglas tube, 4 mm OD, with the ends tied in place so that it lay at its approximate in situ length. This tube was then fastened to the bottom of a cylindrical Plexiglas organ bath so that the duodenum was mounted vertically in the core of the cylindrical tank. Krebs solution was recirculated continuously through the bath, entering through the lumen of the perforated tube which held the duodenum and flowing out through the bottom of the cylindrical tank. This recirculation was effected by a peristaltic finger pump acting on rubber tubing in an external circuit which included a glass heat exchanger. The jacket of the heat exchanger was perfused continuously with warmed water to maintain the Krebs solution in the organ bath at 36.5-37.5”C. The organ bath fluid was aerated continuously with 95 % 02-5 % COZ. The walls of the organ bath contained holes along both the circumference and the longitudinal axis to allow insertion of electrodes. These holes contained rubber O-ring gaskets to seal the electrodes. Silver-silver chloride glass pore electrodes (4) were inserted to touch the serosal surface of the duodenum. Electrode resistance was measured periodically during the experiments and electrodes with resistances greater than 2 k!2 were discarded in view of the input impedance of the amplifiers of 100 kS1. Records of the electrical potential difference were made separately from each electrode against a common grounded reference electrode, a coil of chlorided silver wire placed in the bottom of the cylindrical bath. In order to ascertain whether spike bursts were being satisfactorily recorded by this technique, electrodes were replaced by new ones whenever an isolated ‘
