To determine if CO2-sensitive airway receptors are important in the control of breathing, CO2 was preferentially loaded into the respiratory airways in conscious ponies. The technique involved adding small amounts of 100% CO2 to either the latter one-third or latter two-thirds of the inspiratory air in an attempt to raise CO2 concentrations in the airway dead space independent of the arterial blood. Arterial blood gas tensions (PCO2 and PO2) and pH, as well as respiratory output (minute volume, tidal volume, and respiratory rate), were measured in a series of 20 experiments on 5 awake ponies. Elevation of airway CO2 to approximately 12% by addition of CO2 to the latter portion of the inspiratory tidal volume did not alter either ventilation or arterial blood gases. When CO2 was added earlier in the inspiratory phase to fill more of the airway dead space, a small but significant increase in minute volume (2.1 l X min-1 X m-2) and tidal volume (0.1 l X m-2) was accompanied by an increase in arterial PCO2, arterial PO2, and a fall in pH (0.96 Torr, 10.5 Torr, 0.007 units, respectively). A second series of 12 experiments on 6 awake ponies using radiolabeled 14CO2 determined that the increases in breathing were minimal when compared with the large increase that occurred when these animals inhaled 6% 14CO2 (12.7 l X min-1 X m-2). Also, stimulation of systemic arterial or central nervous system chemoreceptors cannot be eliminated from the response since significant amounts of 14CO2 were present in the arterial blood when this marker gas was added to the latter two-thirds of the inspiratory tidal volume. The results, therefore, provide no evidence for CO2-sensitive airway receptors that can increase breathing when stimulated during the latter part of the inspiratory cycle.
To characterize mechanisms leading to a dietary evoked increase of sucrase (Sa) and lactase (La)' activity by dietary intake of disaccharides [sucrose (S) or lactose (L)], two-monthold rats were fed for 7 days a low carbohydrate diet (LC) [BBA 676:108], then for the next 3 to 72 hours, they were force fed a S or L diet (20 or 40 cal%):Activity of La and Sa increased after 3 hours, but only Sa continued to increase for the next 48 hours. The effect of variation of carbohydrate intake on Sa and La after 12 hours is summarized below.No stubies have been done to evaluate AMA guidelines for Pediatric intravenous vitamins. Two age groups received the AMA suggested dosages as MVI Pediatric: 1) Infants less than 1500 gm (N=21) for 3 wks (65% of Pediatric dose) and 2) Term newborns up to age 10 yrs (N=24) for < 4 wks and, N=8 for 3-6 months). Water soluble vitamin blood levels were normal (B1, B2, B3. Bg) S e m f m~1 2 , pantothenate) in.all patients. Li id soluble vitamins D and E were mainta~ned at normal levels 1 5 -3 9 n q / m l a n d l . Whereas sucrase activity is higher in the upper jejunum than in the lower jejunum, the activity of isomaltase is the same in both segments. To analyze the mechanism involved in this difference, the commonpancreatico-biliary duct was occluded in 3-montk old rats. Control animals were sham operated. Eighteen hours after the operation, the activity of sucrase (SA) and isomaltase [determined as palatinose-hydrolyzing activity (PA)] and immunoreactive amount of sucrase-isomaltase (IRS) were determined in the upper (UJ) and the middle third (LJ) of jejunoileum. Efficacy of the duct ligation was verified by the determination of trypsin activity of each segment. The results (mean i SEM) are summarized below. The decreased SA/PA ratio in LJ was restored by pancreatic duct ligation. Significant linear regression was established between trypsin activity in intestinal lumen and SA/PA ratio (r= -0.801, N=16, p < 0.001). GroupStudies thus show that pancreatic proteases have more effect on the degradation of sucrase than on isomaltase. Parenteral nutrition (TPN) is vital in the nutritional support of infants with surgical GI tract lesions. Rat studies demonstrate decreased small bowel(SB) mucosal enzymes and intestinal atrophy. We studied the effects of TPN during the phase of rapid intestinal growth and development in piglets. Groups of three 6 wk old weaned piglet littermates received for 3 wks awamino acid(8gm/kg/day). glucose(35gm/kg/day), fat(2.5gm/kg/day) solution intravenously(TPN) or by gastrostomy(GF) or were given chow at an equivalent caloric value. No differences were noted inavg weight gain (13-l5gm/kg/day , total serum protein(4.5-4.8gm/dl) , . Comparing the TPN and GF tothe Chow-fed animals, there were: 1) decreased growth of the stomach, SB and pancreas, 2) decreased SB mucosal disaccharidases. The TPN group compared to baseline measurements demonstrated 1) decreased SB weight and length, 2) decreased pancreatic weight. Histology of SB mucosa in TPN animals showed decreased mucosa...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.