A simple, PC-dedicated, implanted digital PIM-radiotelemetric system. Part 2: The multichannel system

The paper, which is a continuation of the previous one, describes a six-channel, PC-dedicated implanted telemetry system, including the schematic drawings, and explanation of all the differences between a single channel and multichannel system approach. The scheme of an additional multichannel analog output, that makes a pure analog recording possible, even without the PC connection, is also presented. Specific methods for both parallel (Centronics) and serial (RS232C) port interfacing are demonstrated and the controlling software principles are discussed. The representative recordings obtained from animal experiments of simultaneous (direct and integrated) multichannel intestinal EMG (MMC) are shown. The device can also be used for the ECG, EEG and uterine smooth muscle electrical activity recording.

A simple, PC-dedicated, implanted digital PIM radiotelemetric system

The short-distance, PC-dedicated implanted telemetry system is described. Schematic drawings of the transmitter and Centronics port interface are given and the main problems of the controlling program are discussed. The interface can be easily converted to serve as an analog output and the method of adaptation is demonstrated. The whole system was tested in animal experiments with two different amplifiers and the examples of resulting direct ECG and both direct and integrated intestinal EMG recordings are included.

Cholecystokinin-8 and vasoactive intestinal polypeptide stimulate exocrine pancreatic secretion via duodenally mediated mechanisms in the conscious pig

The effects of local and peripheral administration of cholecystokinin-8 (CCK-8) and vasoactive intestinal polypeptide (VIP) on basal pancreatic secretion were investigated in conscious pigs. Five pigs (20 +/- 2 kg, mean +/- S.E.M.) were chronically fitted with a T-shaped cannula in the duodenum, and catheters in the pancreatic duct, jugular vein, and right gastroepiploic artery. The arterial catheter was inserted against the bloodstream with its tip opposite the duodenal branch(es) of the right gastroepiploic artery, so that all injected peptides would reach the duodenal arterial circulation excluding the pancreas. Pancreatic secretion during basal conditions (i.e. after an overnight fast) exhibited a characteristic cyclic pattern (cycle duration, 70 +/- 4.2 min). Secretion volume oscillated between 0.2 +/- 0.04 and 4.0 +/- 0.9 ml kg-1 h-1 (P < 0.001), trypsin output between 9.6 +/- 1.9 and 29.1 +/- 4.1 U kg-1 h-1 (P < 0.001) and protein output between 0.36 +/- 0.08 and 9.2 +/- 1.7 mg kg-1 h-1 (P < 0.001). Infusion into the jugular vein for 1 min, during the trough of pancreatic secretion, of either CCK-8 (15 pmol kg-1 min-1) or VIP (7 pmol kg-1 min-1) did not stimulate pancreatic secretion. However, local infusion of an identical dose of CCK-8 or VIP into the duodenal arterial circulation increased the volume, protein output and trypsin output of the pancreatic juice (P < 0.05 to < 0.001). These results indicate that CCK-8 and VIP can stimulate the exocrine pancreas by a duodenally mediated mechanism.

Effect of intraduodenal HCl and soybean extract on pancreatic juice secretion during atropinization and cold vagal blockade in calves

In order to elucidate the mechanisms by which intraduodenal hydrochloric acid (HCl) and soybean extract influence exocrine pancreatic secretion in the young ruminant, we conducted experiments repeatedly on six conscious calves with and without blockade of the extrinsic and intrinsic neural pathways. In the absence of blockade, each of the two stimuli increased the juice volume, the HCl effect being far stronger than that of soybean extract. Intrinsic cholinergic blockade by atropinization blocked the stimulatory work of soybean extract on pancreatic secretion and on HCl-stimulated protein but had a weak effect on the amount of juice evoked by HCl. Temporary vagal blockade by chilling virtually abolished the excitatory effects of both soybean extract and HCl. With or without blockade, duodenal HCl resulted in a noteworthy increase in plasmal secretin and a slight increase in cholecystokinin (CCK). With alimentary proteins, acidification of the duodenum was responsible for both the composition and secretion of pancreatic juice in young calves, generally via neural pathways. Atropine-sensitive nerves of the pancreas totally regulate the intestinal phase of pancreatic juice secretion allied with intraduodenal protein, whereas HCl-dependent excitation of the exocrine pancreas takes place partly via atropine-resistant nerves. However, as hardly any pancreatic juice was secreted independently of the vagi, the vagi are deemed to govern all the postprandial regulatory mechanisms of the exocrine pancreas in the young calf.

Exocrine pancreatic function during cold blockade of the vagus in chronic experiments on calves

Four calves were prepared surgically to investigate the exocrine pancreatic function in chronic experiments. Cooling devices were implanted on both vagi for temporary, reversible, thermal blockade of the conductivity in the nerves. Cooling of the vagi caused significant decreases of volume, total protein content and trypsin activity in pancreatic juice. All of these variables recovered to the control level immediately after the cooling. Results presented indicate an important role of vagally driven information on the exocrine pancreatic secretion in calves.

The effect of adrenal denervation on the metabolic effects of hyperammonemia in sheep

The metabolic effect of intravenous infusion of ammonium chloride (60 mumol/(kg body weight.min] was compared in five sheep before and after adrenal denervation. Adrenal denervation completely abolished the hyperglycemic effect of ammonium chloride, diminished the rise of pyruvate and lactate concentration, and failed to influence the lipolytic effect of NH4Cl. It is suggested that the metabolic effects of ammonia are in a different degree related to the action of ammonia on the central nervous system and (i) the hyperammonemic effect of ammonia completely depends on the neurogenic increase of adrenal medullary hormones; (ii) the rise of blood lactate and pyruvate level observed during hyperammonemia is only partially mediated by adrenaline; and (iii) the lipolytic effect of ammonia ion does not depend on the nerve-controlled secretion of adrenal medullary hormones.

Insulin and the parasympathetic dependence of pancreatic juice secretion in healthy and alloxan diabetic sheep

Pancreatic function was measured in four ewes following vagal stimulation under control conditions and after the induction of alloxan diabetes. The volume and protein content of the pancreatic juice was measured along with simultaneous measurement of blood glucose and plasma insulin. The volume of pancreatic juice and its protein content decreased markedly in the diabetic state and returned to the initial value after insulin treatment. In normal animals, vagal stimulation markedly increased; the volume of pancreatic secretion and its protein content as well as the plasma insulin concentration. In the diabetic animals vagal stimulation caused only a slight increase in the protein content of pancreatic juice and plasma insulin concentration. It is suggested that insulin is probably one of the more important factors directly regulating the secretion of pancreatic juice.