Biomedical subjects

A Planch

Publications and source records attributed to A Planch.

10 recordsLinked to original sources

PubMed1988

Enhancement of peritoneal transport in rats by disrupting stagnant fluid films.

Dialysate comes into contact with the active membrane and remains in contact until the fluid is refreshed. This design exaggerates stagnant fluid films. Dialysis rate studies were done to evaluate transport when stagnant fluid films were disrupted. Following anesthesia, 30 mL of commercial 1.5% glucose dialysate containing 100 mg% urea and 25 mg% inulin warmed to 37.5 C were instilled. Dialysate was sampled at 5, 15, 30, 45, and 60 min after instillation. Experimental rats were vibrated at 25 Hz throughout the study. Diffusive mass-transfer coefficients (MTC mL/min 1000 cm2) were calculated, and control and vibrated group means were tested for differences using Student's t-test. The mean MTC values for control (n = 10) and vibrated groups (n = 12), respectively, were: urea 0.8 +/- 0.04, 1.4 +/- 0.2, p less than 0.01; glucose 0.4 +/- 0.03, 0.6 +/- 0.03, p less than 0.01; insulin 0.2 +/- 0.01, 0.2 +/- 0.01, p = NS. Disrupting stagnant fluid films augments peritoneal transport.

Animals↗

PubMed1988

Measurements of peritoneal surface area in man and rat.

The peritoneal dialysis system is composed of unique membranes. To better understand the contribution of these membranes to peritoneal transport, the peritoneal surface areas were measured in human subjects and rats.

Animals↗

PubMed1987

Systems of membranes involved in peritoneal dialysis.

To evaluate whether the viscera contribute to the system of membranes used in peritoneal dialysis, dialysis rate studies were performed comparing control rats (n = 9, mean peritoneal area 509 +/- 38 cm2) with eviscerated rats (n = 12, mean peritoneal area 200 +/- 123 cm2). The mass transfer coefficient (MTC) and absorption from the peritoneal cavity were calculated for urea, creatinine, and inulin, which had been added to commercially available 1.5% hydrous dextrose dialysate. Rates of peritoneal blood flow to the peritoneal membranes remaining after evisceration were similar for both groups. Urea, creatinine, glucose, and inulin were used as markers to compare control and eviscerated animals. The MTC results were (in milliliters per minute, mean +/- SEM): urea 3.0 +/- 0.3, 4.1 +/- 0.5 (P less than 0.01); creatinine 1.4 +/- 0.2, 2.0 +/- 0.2 (P less than 0.05); glucose 1.2 +/- 0.3, 1.7 +/- 0.2 (P less than 0.09); inulin 0.3 +/- 0.02, 0.6 +/- 0.1 (P less than 0.01); and MTC inulin/MTC urea 0.16 +/- 0.01, 0.14 +/- 0.01. Absorption of urea, creatinine, glucose, and inulin from the peritoneal cavity was only 10% to 23% greater among control animals. Whether the results were caused by nonparticipation of the intestinal viscera or other mechanisms, such as improved contact between dialysate and membrane, awaits further study.

Animals↗

PubMed1986

The importance of the abdominal viscera to peritoneal transport during peritoneal dialysis in the dog.

The authors sought to evaluate the dialyzing surfaces important for peritoneal dialysis. They reasoned that the most definitive way to evaluate whether any of the gut and associated membranes contributed to transport was to see if transport changed when they were removed. Paired studies measuring rates of peritoneal uptake of glucose, urea, and inulin were carried out in dogs. In the morning, the animals were tested with all peritoneal membranes intact. In the afternoon, the studies were repeated after evisceration. The mass transfer coefficients (MTC ml/min)--glucose (viscera 4.4 +/- 0.7, no viscera 4.9 +/- 0.3)--urea (viscera 16.8 +/- 2.4, no viscera 13.8 +/- 1.0);--inulin (viscera 1.6 +/- 0.6, no viscera 2.2 +/- 0.7) were not changed nor was the amount of mass absorbed significantly different. MTC and peritoneal absorption were unaffected by omentectomy, mesenterectomy, or evisceration. Whether these results were due to nonparticipation of these structures in peritoneal transport or other mechanisms await further studies.

Absorption↗

PubMed1985

Evaluation of a peritoneal dialysis solution containing polymer.

Glucose is used in peritoneal dialysate to produce the gradient for ultrafiltration. The peritoneal membrane's low reflection coefficient for glucose imposes a demand for high transmembrane concentrations, perhaps adding unwanted body burden of glucose. A polymer with a lower permeation rate used as an osmotic agent would circumvent this. We evaluated the mass transfer coefficient (mtc), T1/2 disappearance from the peritoneal cavity and ultrafiltration capabilities of a 900 dalton (Mn) starch derived polymer. We compared an 8% (455 mOsm/L) and a 10% (484 mOsm/L) polymer (Pol) solution to available dialysate solutions containing 2.5% (399 mOsm/L) and 4.25% (491 mOsm/L) X glucose (Glc). The dialysate compositions were otherwise similar. Using a randomized complete block design, 5 anephric dogs maintained on chronic peritoneal dialysis were studied. The mtc (ml/min) was greater for the glucose than the polymer solutions (p less than 0.05): 2.5%-13 and 4.25%-14 vs 8%-5 and 10%-6. The T1/2 disappearance (min) was also greater (p less than 0.05): 2.5% Glc-112 and 4.25% Glc-111 vs 8% Pol-281 and 10% Pol-252. Over a 180 min. period the 2.5% glucose solution generated the least volume of ultrafiltrate (ml, p less than 0.05): 2.5% Glc-113 and 4.25% Glc-589 vs 8% Pol-640; 10% Pol-912. We conclude that the lower permeation rate of the polymer yields ultrafiltration at a lower dialysate osmolality. A polymer solution may be a feasible alternative to glucose.

Animals↗

PubMed1985

Substitution of a starch polymer for glucose in peritoneal dialysis.

We compared a starch-derived polymer (molecular weight = 900) as the osmotically active agent in peritoneal dialysate (3 and 6% solutions) to results obtained with commercially available glucose dialysate (1.5 and 4.25%). 12 dogs were dialyzed with glucose for 7 days, and 9 received the polymer for 5 days. For dialysate exchanges with an intraperitoneal residence of 240 min the 1.5 and 3% solutions generated similar volumes of ultrafiltrate as did the 4.25 and 6% solutions. However, for exchanges of 960 min the 1.5% dialysate was significantly reabsorbed when compared to the other dialysate concentrations. The serum polymer concentration increased with continued dialysis. The rate of transfer from dialysate to serum in man must still be determined. The lower diffusivity of the polymer will certainly be evidenced. For certain clinical applications where diminished ultrafiltration occurs, the polymer may be of benefit to man.

Animals↗

PubMedDate not supplied

Intraperitoneal feeding.

This study evaluated the peritoneal cavity as the sole route for alimentation in 300 g growing rats. Initial studies demonstrated that a solution of high osmolality was required to provide sufficient calories. A nutrient solution was formulated by mixing 20% glucose with electrolytes (10 ml) and 8.5% amino acids with electrolytes (20 ml). Instilling 30 ml of nutrient solution induced an IP volume of 60 ml, which was absorbed in 24 hours. Rats were studied in four groups for 7 days. One group received nutrient solution IP (n = 10); a second group received the same amount PO (n = 10); the third group received electrolytes IP (n = 10); and a fourth group was fed rat chow PO (n = 10). Rats fed this nutrient solution (IP and PO) were acclimatized by administering one third of their required nutrient the first 4 days. On the next 3 days they received two thirds of their required nutrient. Both groups fed nutrient solution (IP and PO) lost 23% body weight. Electrolyte and rat chow fed groups lost 26% and gained 8% of body weight, respectively. Due to the high osmolality (1200 mOsm/L) of this nutrient solution, sufficient food could not be delivered via the peritoneal cavity to adequately feed growing rats. Studies were then initiated to formulate another nutrient solution that contained lipids. This solution (678 mOms/L) contained 20% glucose with electrolytes (10 mls), 8.5% amino acids with electrolytes (20 ml), and 10% lipids without electrolytes (30 ml). Glucose and amino acids contained the same electrolyte concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMedDate not supplied

Absorption of sulfamethoxazole and albumin from the peritoneal cavity.

The rates of disappearance of sulfamethoxazole and albumin from the peritoneal cavity were measured in humans. Albumin was added to the peritoneal cavity in concentrations commonly found during peritonitis (250-500 mg/100 ml) to ascertain if protein binding within the peritoneal cavity inhibited absorption from the peritoneal cavity. There were no statistical differences between the removal rates; 64-70% of the administered dose was absorbed after 180 min of intraperitoneal residence. The addition of albumin to the peritoneal cavity did not alter absorption of sulfamethoxazole. The total protein removed in dialysate effluent in the absence of albumin was 1,653 +/- 906 mg. The protein losses when albumin was added to dialysate [( albumin + control losses] - losses in dialysate drainage) were 1,037 +/- 2,305 mg and 1,364 +/- 1,653 mg for the 6 and 12 g studies.

Adult↗

PubMedDate not supplied

Intraperitoneal insulin--a dose response curve.

To determine a dose response curve for intraperitoneal (i.p.) insulin using Sprague-Dawley rats, human insulin was administered i.p. in 1.5% glucose dialysate at the following doses: 10 U (2.19 U/100 g body wt); 5U (1.23 U/100 g body wt); 2 U (0.49 U/100 g body wt); 1 U (0.27 U/100 g body wt). A bolus injection of glucose was given to elevate blood sugar, followed by infusion of D20%. Blood sugar was maintained at 250 mg/dl by checking at 10 minute intervals and adjusting the IV infusion. Dialysate with regular insulin was instilled after blood sugar was constant for 20 minutes. The end-point was the amount of glucose to maintain a blood sugar of 250 mg/dl after instillation of dialysate and regular insulin. Mean blood sugars were similar within and between each dose group. The effect of regular insulin was noted within 10 minutes. The amount of glucose used with the IV dose differed from all other (p less than 0.05). The amount used by the 5 and 10 U doses of i.p. insulin were similar. Increasing amounts of glucose are required to maintain the blood sugar at increasing doses of intraperitoneal regular insulin up to 5 U. Thus, there appears to be a dose response curve for i.p. insulin.

Animals↗

PubMedDate not supplied

The minimal importance of the hollow viscera to peritoneal transport during peritoneal dialysis in the rat.

The authors investigated whether the abdominal viscera are important surfaces for peritoneal transport by performing peritoneal dialysis in rats without their abdominal viscera and again when the parietal walls were shielded from contact with dialysate. Urea, creatinine, glucose, and inulin were added to the peritoneal cavity and the percentage of the administered dose absorbed was calculated. Controls with and without parietal shields only absorbed 11% more urea and creatinine, 5-15% more glucose, and 7-12% more inulin, respectively, than eviscerated rats. The findings raise the possibility that the abdominal contents do not account for most of peritoneal transport.

Absorption↗