Effect of protamine on the permeability and structure of rat peritoneum

Local Anesthetic -Bupiv Acaine Increases the Peritoneal Transport of Solutes. Part I: In Vivo Study

A local anesthetic -bupivacaine was used in concentration 0.25 mmol/l in the dialysis fluid during peritoneal dialysis in rabbits. Bupivacaine increased the mean peritoneal clearance of urea by 33% and of inulin by 53%. The effect of the anesthetic persisted during next exchanges, performed without the drug. Bupivacaine given intraperitoneally, did not decrease blood pressure.

Peritoneal dialysis is used widely for treatment of renal failure (1). During the last few years, many attempts have been made to find a substance, which would increase the efficiency of peritoneal dialysis (2, 4). In the past we observed that procaine added to the fluid augments peritoneal solute clearance (5). Local anesthetics in the peritoneal cavity influence both the mesothelium and the vascular system. In the present study we used bupivacaine a long-acting, tissue-bound local anesthetic as the adjunct during peritoneal dialysis in rabbits.

Peritoneal Ultrafiltration after Chronic Exposure to Dialysis Fluid

Eleven rats were given twice-daily intraperitoneal injections of 20 mL of dialysis fluid containing 4.5% glucose for 6 weeks. The peritoneal ultrafiltration capacity of this group was compared with that of a control group of 10 rats that had received no injections by measuring the volume and glucose concentration of the dialysate remaining in the peritoneal cavity 2 hours after injection. Animals that had received injections of dialysis fluid showed significant loss of peritoneal ultrafiltration: volume of dialysate remaining in the control group was 31 (13–35) mL, and in the experimental group was 25 (11–45) mL, with p<0.02 (Mann-Whitney). This was associated with enhanced glucose absorption: glucose absorbed by the control group was 382 (312–706) mg, and 595 (435–738) mg in the experimental group (p<0.002, Mann-Whitney).

Intracellular Calcium Ions Modulate Permeability of the Peritoneal MesotheliumIn Vitro

The authors studied the in vitro effect of a calcium-channel-blocker -verapamil, local anesthetic -bupivacaine and a calcium ionophore -A23187 on the permeability of the monolayer mesothelium from the rabbit's mesentery. Verapamil and bupivacaine increased transmesothelial flux of calcium while A23187 increased calcium transport only transiently. Verapamil augmented the permeability of the mesothelium to inulin and urea. However A23187 decreased the transmesothelial flux of inulin only whereas it increased the transport of urea. From this study we have concluded, that intracellular calcium may determine the permeability of the peritoneal mesothelium.

Various important biological processes like muscle contraction, secretion of transmitters and hormones, and control of epithelial permability seem to be dependent on intracellular calcium-ion activity (1–4). Our previous paper suggested that a local anesthetic, bupivacaine, produces its effect on the peritoneal mesothelium through interaction with the cytoskeleton of the epithelial cells, and with the mem brane's calcium transport (5). In addition Palant et al found that the permeability of another leaky epithelium, that from the Necturus gallbladder, depends on the extracellular calcium concentrations and may be altered by drugs, which interfere with the entrance of these ions into the epithelial cells (6). Therefore, we decided to study the role that calcium ions may play in the transport of solutes across the peritoneal mesothelium in vitro.

Local Anesthetic -Bupiv Acaine Increases the Transperitoneal Transport of Solutes. Part II: In Vitro Study

The local anesthetic, bupivacaine, alters the mesothelial permeability to urea and inulin. The effect is biphasic; an initial transient decrease is followed by an increase in permeability of the membrane to both solutes. Cytochalasill B and colchicine can mimic partially the action of bupivacaine, but without the initial decrease in the mesothelilal permeability. Similar to bupivacaine, verapamil also evokes a biphasic effect on the trallsmesothelial nux of urea and inulin. In conclusion bupivacaine induces changes both in trallscellular and intercellular pathways, due to its interaction with calcium ions and the cytoskeleton of the mesothelial cells.

Mesothelium is one of the barriers detennining transfer of solutes from blood to the peritoneal cavity during peritoneal dialysis (1). It has been demonstrated that the function of the mesothelial cells may influence the efficiency of the peritoneal dialysis (2–4). Earlier we showed that bupivacaine added to the dialysis fluid in a concentration of 0.25 mmol/l increased the removal of urea and inulin via the peritoneum (5). Our findings suggest that the effect of bupivacaine depended primarily on its action on the mesothelium.

We perfonned a series of in vitra experiments on the monolayer mesothelium taken from the ileal rabbit's mesentery in order to define the character of changes induced in this structure by bupivacaine. This paper describes our findings.

Reversal of protamine reaction with heparin

We recently encountered a patient who had severe cardiovascular collapse following administration of protamine. This severe protamine reaction was resistant to all forms of pharmacological therapy except for heparinization. Heparinization resulted in immediate reversal of the cardiovascular collapse.

Protamine-Induced Epithelial Barrier Disruption Involves Rearrangement of Cytoskeleton and Decreased Tight Junction-Associated Protein Expression in Cultured MDCK Strains

Natural and synthetic polycationic proteins, such as protamine, have been used to reproduce the tissue injury and changes in epithelial permeability caused by positively charged substances released by polymorphonuclear cells during inflammation. Protamine has diverse and often conflicting effects on epithelial permeability. The effects of this polycation on the distribution and expression of tight junction (TJ)-associated proteins have not yet been investigated. In this work, we examined the influence of protamine on paracellular barrier function and TJ structure using two strains of the epithelial Madin-Darby canine kidney (MDCK) cell line that differed in their TJ properties ("tight" TJ-strain I and "leaky" TJ-strain II). Protamine induced concentration-, time- and strain-dependent alterations in transepithelial electrical resistance (Rt) only when applied to apical or apical+basolateral monolayer surfaces, indicating a polarity of action. In MDCK II cells, protamine (50 microg/ml) caused a significant increase in Rt that returned to control values after 2 h. However, the treatment of this MDCK strain with a higher concentration of protamine (250 microg/ml) significantly decreased the Rt after 30 min. In contrast, treated MDCK I monolayers showed a significant decrease in Rt after apical treatment with protamine at both concentrations. The protamine-induced decrease in Rt was paralleled by an increase in the phenol red basal-to-apical flux in both MDCK strains, suggesting disruption of the paracellular barrier. Marked changes in cytoskeletal F-actin distribution/polymerization and a significant reduction in the junctional expression of the tight junctional proteins occludin and claudin-1 but subtle alterations in ZO-1 were observed following protamine-elicited paracellular barrier disruption. In conclusion, protamine induces alterations in the epithelial barrier function of MDCK monolayers that may involve the cytoskeleton and TJ-associated proteins. The various actions of protamine on epithelial function may reflect different degrees of interaction of protamine with the plasma membrane and different intracellular processes triggered by this polycation.

Abdominal peritoneum as a defense organ: analysis of ICAM-1 expression in the LPS-stimulated rat

To investigate the immune environment of the peritoneal cavity, ICAM-1 (intercellular adhesion molecule) expression on the apical surface of the hepatic peritoneum of LPS (lipopolysaccharide) stimulated rats was analyzed ultrastructurally and chronologically with immunoTEM&SEM. ICAM-1 expression was restricted to the side of microvilli of the mesothelial cells. Microvilli demonstrated bulbous tips and included fuzzy coats and strands. Bulbous tips sometimes expressed the antigen, but fuzzy coats and strands did not. Intervillar cell surfaces lacked its expression. Although ICAM-1 expression increased eightfold 24 hr after stimulation, the selective expression remained unchanged. These results suggest that microvilli are closely associated with cell migration in the peritoneal cavity through adhesion molecules that establish a road for migration.

Phosphatidylcholine synthesis by peritoneal mesothelium: its implications for peritoneal dialysis

This study investigated the possibility that the peritoneum is capable of synthesizing phosphatidylcholine (PC), a lubricant surfactant, in an amount similar to that produced by pulmonary alveoli. The synthesis of PC by rat lung (positive control), liver (negative control), and transparent mesentery (test tissue) was determined by in vitro incubation of these tissues in the presence of (methyl-14C) choline chloride for three hours at 37 degrees C in Warburg flasks. All lipid material present in tissue and incubation media was extracted by the Folch technique. Carrier egg PC was added to each sample and total PC was isolated using high performance thin-layer chromatography. The PC fractions were counted for total radioactivity. No statistically significant difference was observed between the mean radioactive value for mesenteric tissue compared with lung tissue. The mean radioactive value for liver when compared with mesenteric and lung tissue was significantly lower (P less than 0.001). Thus, under the conditions of the experiment, we have demonstrated for the first time that peritoneal tissue is capable of synthesizing PC in amounts similar to that produced by the lung. Electron microscopy of transparent mesentery (test tissue) showed that mesothelium constituted the bulk of the cell population. Therefore, it is most likely that the PC that has been detected in peritoneal fluid is produced by the mesothelial cell. These findings are of significant relevance to developing concepts on the role of surfactant phospholipids in the physiology of peritoneal dialysis.

Protamine alters apical membrane K+ and Cl- permeability in gallbladder epithelium

Protamine addition to the solution bathing the mucosal side of Necturus gallbladder epithelium (25-100 mg/l) caused depolarization of both cell membranes, a mucosa-negative change in transepithelial voltage, an increase in the apical membrane resistance (Ra) followed by a decrease, and a monotonic increase in transepithelial resistance (Rt). In protamine (25 mg/l), the change in apical membrane voltage elicited by elevating mucosal solution [K+] from 2.5 to 92.5 mM was reduced from 66 +/-2 to 38 +/- 5 mV (P less than 0.001). The K+-induced fall in Ra was also reduced in protamine. These effects could also be elicited by elevating mucosal solution [K+] simultaneously with the addition of protamine and by transient addition of protamine during exposure to the high K+ medium. The effect of protamine on the electrodiffusive Cl- permeability of the apical membrane (PCl) was studied both in control and forskolin-treated tissues. In the absence of forskolin, the hyperpolarization of Vmc produced by lowering mucosal [Cl-] to 10 mM was reversed to a small depolarization; in forskolin, the initial depolarization produced by lowering [Cl-] was significantly increased. Finally, exposure to protamine in the absence of forskolin produced an initial fall in intracellular Cl- activity. Our results indicate that protamine decreases apical membrane K+ permeability and increases apical membrane PCl. The time course of the effects of protamine suggests the possibility of an initial effect on surface potential, followed by secondary actions mediated by intracellular events.

Protamine reversibly decreases paracellular cation permeability in Necturus gallbladder

Protamine, a naturally occurring arginine-rich polycationic protein (pI 9.7 to 12), was tested in Necturus gallbladder using a transepithelial AC-impedance technique. Protamine sulfate or hydrochloride (100 micrograms/ml = 20 microM), dissolved in the mucosal bath, increased transepithelial resistance by 89% without affecting the resistance of subepithelial layers. At the same time, transepithelial voltage (psi ms) turned from slightly mucosa-positive values to mucosa-negative values of approximately +1 to -5 mV. The effect of protamine on transepithelial resistance was minimal at concentrations below 5 micrograms/ml but a maximum response was achieved between 10 and 20 micrograms/ml. Resistance started to increase within 1 min and was maximal after 10 min. These effects were not inhibited by serosal ouabain (5 X 10(-4) M) but could be readily reversed by mucosal heparin. The sequence of protamine effect and heparin reversal could be repeated several times in the same gallbladder. Mucosal heparin, a strong negatively charged mucopolysaccharide, or serosal protamine were without effect. Mucosal protamine reversibly decreased the partial ionic conductance of K and Na by a factor of 3, but did not affect Cl conductance. Net water transport from mucosa to serosa was reversibly increased by 60% by protamine. We conclude that protamine reversibly decreases the conductance of the cation-selective pathway through the tight junction. Although this effect is similar to that reported for 2,4,6-triamino-pyrimidinium (TAP), the mechanism of action may differ. We propose that protamine binds to the apical cell membrane and induces a series of intracellular events which leads to a conformational alteration of the tight junction structure resulting in decreased cationic permeability.

The effects of bovine serum albumin and a form of cationised ferritin upon the molecular selectivity of the walls of single frog capillaries

Single frog mesenteric capillaries have been perfused with Ringer solutions containing the neutral macromolecule Ficoll 70 at a concentration of 40 mg ml-1, while the tissues have been washed with Ringer solution containing no macromolecules but otherwise of similar composition. The effective osmotic pressures (sigma delta II) set up across the capillary wall by the Ficoll 70 were used to assess the wall's molecular selectivity. The hydraulic conductivities, Lp, of the capillary walls were also measured. In seven capillaries the addition of bovine serum albumin (BSA) to the perfusate at concentrations of 1 and 10 mg ml-1 increased sigma delta II from a mean value of 7.14 +/- 1.81 cm H2O to one of 18.71 +/- 2.33 cm H2O and at the same time halved Lp. In another eight capillaries, the addition of a form of cationised ferritin (CF) to the perfusate at a concentration of 1 mg ml-1 increased sigma delta II from a mean value of 5.69 +/- 0.87 cm H2O to one of 16.69 +/- 0.262 cm H2O and reduced Lp to between a third and a half of its original value. In a further seven capillaries, the addition of native ferritin at a concentration of 1 mg ml-1 to the perfusate had no effect on either sigma delta II or Lp. It is suggested that both CF and BSA increase the reflection coefficients of capillary walls to Ficoll 70 by binding to the surface coat of the endothelium. The results are discussed in terms of a development of the fiber matrix theory of Curry and Michel (1980).

Peritoneal permeability in the rat: modulation by microfilament-active agents

A model of peritoneal dialysis in the rat was used to determine the effects of cytochalasins on ultrastructure and peritoneal permeability to molecules of varying molecular weight. The permeability to urea, inulin, and plasma albumin were determined after intraperitoneal administration of cytochalasin B (2 to 10 X 10(-6) M) and cytochalasins D and E (2 X 10(-6) M). Cytochalasin B (20 X 10(-6) M) increased the permeability to inulin, urea, and albumin by 30, 60, and 150%, respectively. These effects were, to a large degree, reversible. Cytochalasins D and E produced greater increments in permeability for all molecules; this increase was only partially reversible. Ultrastructure analysis by scanning electron microscopy revealed extensive development of membrane protuberances (zeiotic knobs) on mesothelial cells exposed to cytochalasin B. A return to a normal apical cell surface was apparent although incomplete at 24 hr. Tight junctions were not grossly altered and major changes in intramembranous junctional strands were not observed. The major effect of cytochalasins on the cell surface may be responsible for the increased permeability to urea, predominately a transcellular probe. Inulin, which follows a paracellular route, was less affected. Altered protein permeability may be due to the action of cytochalasin on the exposed capillary endothelium in subdiaphragmatic areas where the mesothelium is discontinuous.

Augmentation of peritoneal dialysis clearance with procaine

Local anesthetic procaine in a 0.25% concentration was used as the adjunct to the dialysis fluid during peritoneal dialysis in rabbits. Procaine increased peritoneal clearance of urea (2.213 +/- 0.187 ml/min to 3.544 +/- 0.41 ml/min) and inulin (0.528 +/- 0.079 ml/min to 0.852 +/- 0.213 ml/min). Effect of the drug persisted, despite its lack, during the following cycles. Procaine influenced transmesothelial transfer of urea and inulin in vitro. The effect of the drug was biphasic. During the first 20 min a decrease of both solutes fluxes was observed. Then the transport rate of urea and inulin started to grow. The effect of procaine was independent of the membrane's side to which the drug was added. At least two sites of procaine action (vascular system and mesothelium) during peritoneal dialysis are proposed.

Adverse reactions to protamine sulfate following cardiac surgery

We report four patients who developed severe adverse reactions to protamine sulfate following cardiac surgery. Two types of reactions were seen. First, an immediate anaphylaxis which is a complement-dependent IgG antibody-mediated reaction. In the literature, 80% of patients who had similar reactions have had previous exposure to protamine. All patients adequately tested had positive skin tests and there is 6% mortality. The second reaction to protamine during cardiac surgery is characterized by delayed onset and profound vascular damage presenting as noncardiogenic pulmonary edema or total vascular collapse with prolonged hypotension and anasarca. These patients have negative skin tests and in our studies, no evidence of antibody mediated reaction, suggesting some other mechanisms may play a part. The mortality is high (30% of patients reported) and survivors have significant morbidity.