SEARCH · PubMed Health

Results for “PHOSPHOLIPASE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,297 records · Page 72Linked to original sources

PubMed1995

Phospholipase D from soybean (Glycine max L.) suspension-cultured cells: purification, structural and enzymatic properties.

Phospholipase D (phosphatidylcholine phosphatidohydrolase EC 3.1.4.4) from soybean (Glycine max L.) suspension-cultured cell was purified around 1,200-fold to homogeneity by acetone precipitation, Macro-Prep High Q anion exchange, and octyl-Sepharose CL-4B affinity chromatography. The purified enzyme released 1,600 mumol of choline per min per mg of protein. The enzyme is monomeric with a molecular mass of 92 kDa, as estimated by SDS-PAGE. One of the most interesting characteristics of the purified soybean phospholipase D was the dependence of the pH optimum on the Ca2+ ion concentration in the assay. With 10 mM, 20 mM and 40 mM Ca2+ ions, the optima were at pH 7.5, 6 and 5.5, respectively. The specific adsorption of phospholipase D onto octyl-Sepharose gel suggests that the molecule becomes more hydrophobic in the presence of Ca2+ ions. The amino acid sequence of the first 18 N-terminal residues of soybean phospholipase D revealed a high degree of homology with those previously published for cabbage leaf and castor bean endosperm enzymes. Western blots of the soybean phospholipase D showed an immunoreactivity with antibodies raised against a synthetic peptide corresponding to the 15 N-terminal amino acid residues of phospholipase D from cabbage leaves.

Amino Acid Sequence↗

PubMed1991

Activity of phospholipase C and release of prostaglandin F2 alpha by endometrial tissue from ovariectomized ewes receiving progesterone and estradiol.

Progesterone and estradiol interact to regulate secretion of prostaglandin (PG) F2 alpha from the ovine endometrium in response to oxytocin. Two experiments were conducted to determine if these effects were due to changes in activity of phospholipase C or in the second messenger responsive pathways that regulate production of PGF2 alpha. In both experiments, ovariectomized ewes were assigned to one of four treatment groups (control, estradiol, progesterone, progesterone and estradiol). Steroids were administered, in vivo, to mimic the changes that occur during the estrous cycle. On Day 16 of steroid treatment, endometrial tissue was collected and incubated, in vitro, to measure activity of phospholipase C and release of PGF2 alpha. Treatment with progesterone, in vivo, enhanced basal and oxytocin-induced activity of phospholipase C and release of PGF2 alpha, in vitro. Estradiol suppressed oxytocin-induced activity of phospholipase C, both in the presence and absence of progesterone. In contrast to its effects on phospholipase C, estradiol inhibited basal and oxytocin-induced release of PGF2 alpha when administered alone, but not when administered with progesterone. Steroids had similar effects on the release of PGF2 alpha induced by phorbol 12-myristate 13-acetate and A23187. It was concluded that progesterone and estradiol regulate endometrial release of PGF2 alpha by affecting both the activity of phospholipase C and its associated second messenger responsive pathways that may regulate production of PGF2 alpha.

Animals↗

PubMed1989

Salt-induced and spontaneous hyperactivity of phospholipase C in primary hypertension.

Previous studies from our laboratory have shown that platelets from both spontaneously hypertensive rats and essential hypertensive patients exhibited an increased thrombin-triggered phospholipase C activity compared with normotensive subjects. In order to determine the relationship between phospholipase C and hypertension we investigated this enzymatic activity in Dahl salt-resistant (Dahl R/Jr) and salt-sensitive (Dahl S/Jr) rats fed either a low- or a high-NaCl diet, and in DOCA-NaCl hypertensive rats. Phospholipase C activity was increased in the Dahl S/Jr rats fed a high-NaCl diet compared to a low-NaCl diet. This difference was not observed in the Dahl R/Jr rats, irrespective of diet. Likewise, phospholipase C activity was similar in the DOCA-NaCl hypertensive rats compared with their controls. Our results indicate that the increased platelet phospholipase C activity was not a consequence of either the blood pressure elevation or the high NaCl intake and was probably of genetic origin. While the increased phospholipase C activity was not correlated with blood pressure, the enhanced enzymatic activity in Dahl S/Jr hypertensive rats may be involved in the elevation of blood pressure and may be NaCl-regulated.

Animals↗

PubMed1987

Phospholipase C activity in human endometrium: its significance in endometrial pathology.

Phospholipase C activity was measured in human endometrium using an assay based on the release of total labelled water soluble products (inositol, inositol phosphates) from L-3-phosphatidyl-[2-3H] inositol. The enzyme was shown to be calcium dependent and to have an optimum pH of 5.5. There was no difference between proliferative phase and secretory phase endometrium with respect to phospholipase C activity either in women with normal menstrual blood loss (proliferative phase: 3.7 +/- 0.7 (mean +/- SD), secretory phase: 4.5 +/- 2.0 nmol/mg protein/min) or in those complaining of severe menorrhagia (proliferative phase: 5.8 +/- 2.8, secretory phase: 7.0 +/- 2.8 nmol/mg protein/min). However, women complaining of severe menorrhagia had significantly higher endometrial phospholipase C activity than those in the normal group (P less than 0.01 and P less than 0.02 for proliferative and secretory phases respectively). Endometrial phospholipase C activity was also elevated in the presence of other gynaecological disorders, e.g. dysmenorrhoea, adenocarcinoma of the cervix and endometrial hyperplasia. The results indicate that phospholipase C activity in human endometrium is not related to the stage of the menstrual cycle but that in the presence of menorrhagia and other gynaecological disorders, activity is increased. Phospholipase C could be implicated in the generation of arachidonic acid for prostaglandin synthesis which may in turn be associated with these abnormalities.

Adult↗

PubMed1997

Study of fatty acid specificity of sunflower phospholipase D using detergent/phospholipid micelles.

The fatty acid specificity of phospholipase D purified from germinating sunflower seeds was studied using mixed micelles with variable detergent/phospholipid ratios. The main advantage of this approach is that since the substrate is integrated in the detergent micelles, comparisons can be made between the kinetic constants of a wide range of phosphatidylcholine (PtdCho) compounds with various fatty acid contents. Phospholipase D is subject to interfacial activation as it is most active on water-insoluble substrates. It is not active on sphingomyelin and only slightly on lysophosphatidylcholine. By fitting the curves based on the experimental kinetic data, the interfacial dissociation constant of phospholipase D, the maximum hydrolysis rate Vm and the kinetic constant Km(B), were determined with the micellar substrate. The specificity of various substrates was examined by comparing the Vm/Km(B) values, and it was noted that sunflower phospholipase D is most active on medium-chain fatty PtdCho compounds. With long-chain natural phospholipids, the specificity of phospholipase D was slightly dependent on the level of fatty acid unsaturation. The pure enzyme was able to hydrolyse the sunflower phospholipids present in mixed detergent micelles but not the phospholipids integrated in the natural sunflower oil body structure. We concluded, however, that during the germination of sunflower seeds, phospholipase D might be involved in the degradation of oil bodies, since other factors present in crude seed extracts may make phospholipids accessible to the enzyme.

Calcium↗

PubMed2006

Serotonin 5-HT(2A) receptor activation induces 2-arachidonoylglycerol release through a phospholipase c-dependent mechanism.

To date, several studies have demonstrated that phospholipase C-coupled receptors stimulate the production of endocannabinoids, particularly 2-arachidonoylglycerol. There is now evidence that endocannabinoids are involved in phospholipase C-coupled serotonin 5-HT(2A) receptor-mediated behavioral effects in both rats and mice. The main objective of this study was to determine whether activation of the 5-HT(2A) receptor leads to the production and release of the endocannabinoid 2-arachidonoylglycerol. NIH3T3 cells stably expressing the rat 5-HT(2A) receptor were first incubated with [(3)H]-arachidonic acid for 24 h. Following stimulation with 10 mum serotonin, lipids were extracted from the assay medium, separated by thin layer chromatography, and analyzed by liquid scintillation counting. Our results indicate that 5-HT(2A) receptor activation stimulates the formation and release of 2-arachidonoylglycerol. The 5-HT(2A) receptor-dependent release of 2-arachidonoylglycerol was partially dependent on phosphatidylinositol-specific phospholipase C activation. Diacylglycerol produced downstream of 5-HT(2A) receptor-mediated phospholipase D or phosphatidylcholine-specific phospholipase C activation did not appear to contribute to 2-arachidonoylglycerol formation in NIH3T3-5HT(2A) cells. In conclusion, our results support a functional model where neuromodulatory neurotransmitters such as serotonin may act as regulators of endocannabinoid tone at excitatory synapses through the activation of phospholipase C-coupled G-protein coupled receptors.

Animals↗

PubMed2003

Aquaporin 3 colocates with phospholipase d2 in caveolin-rich membrane microdomains and is downregulated upon keratinocyte differentiation.

Aquaporin 3 is a channel that transports both water and glycerol. Aquaporin 3-deficient mice exhibit skin defects, including decreased glycerol content and impairment of water holding capacity, barrier recovery, and wound healing. Whether aquaporin 3 and its glycerol transporting capacity are involved in regulating keratinocyte function, we have previously shown that phospholipase D2 can metabolize phospholipids in the presence of glycerol to yield phosphatidylglycerol. We hypothesized that aquaporin 3 is involved in the regulation of keratinocyte function by a mechanism involving the interaction between aquaporin 3 and phospholipase D. Using sucrose gradient centrifugation, immunoprecipitation analysis, and confocal microscopy, we found that aquaporin 3 and phospholipase D2 colocalized in caveolin-rich membrane microdomains. In addition, aquaporin 3 expression was downregulated at the transcriptional level and glycerol uptake was reduced upon primary mouse keratinocytes to differentiation in response to an elevated extracellular calcium concentration or 1,25-dihydroxyvitamin D3. Our results suggest that aquaporin 3 and phospholipase D2 form a signaling module in lipid rafts, where aquaporin 3 transports glycerol to phospholipase D2 for the synthesis of phosphatidylglycerol. Phosphatidylglycerol, as a bioactive lipid, could potentially mediate the effects of the aquaporin 3-phospholipase D2 signaling module, with aquaporin 3 as a modulatory unit, in the regulation of keratinocyte function.

Animals↗

PubMed1977

The effect of phospholipase C on rat blood platelets in vivo.

Rat blood platelets were treated with phospholipase C in vitro or phospholipase C was injected i.v. to rats. In both cases its effect on the functions of the platelets in vivo has been studied. No change was found in primary bleeding time or in platelet survival. Treatment with phospholipase C gave a moderate reduction of ADP-induced platelet aggregation in the pulmonary circulation whereas the aggregation induced by thrombin was unchanged. Iv. injection of phospholipase C caused a rapid, very moderate and transient increase of 51Cr-activity in the lungs without concomitant overt respiratory distress. A moderate increase in 51Cr-activity was noted in liver and kidney 24 and 48 h after injection of phospholipase C. This may be caused by a slightly increased leakage of 51Cr-labelled material from the platelets during exposure to phospholipase C.

Adenosine Diphosphate↗

PubMed1975

The phospholipase activity of sheep pancreatic juice.

Sheep pancreatic juice was found to contain at least two enzymes which hydrolysed biliary lecithin. One enzyme was heat and acid labile and hydrolysed the fatty acid from position 1 (phospholipase A1); the other was heat and acid stable hydrolysing the fatty acid at position 2 (phospholipase A2). Lysophospholipase activity was also present. The phospholipases were active at pH values greater than 4.2, and would therefore function in the acid conditions (pH 3-6) of the sheep small intestine. The activity of the pancreatic phospholipases, and A2 in particular, was dramatically stimulated by the presence of the secretions of Brunner's glands which could be important in accelerating the hydrolysis of biliary lecithin in the lumen of the intestine. Phospholipase A1 was sensitive to acid in the range pH 2.5-3.5 and could therefore be partially inactivated by abomasal digesta; but phospholipase A2 was resistent to acid treatment.

Animals↗

PubMed1972

The action of phospholipases on the inner and outer surface of the squid giant axon membrane.

1. The effects of phospholipases on resting potential, action potential and membrane ionic conductances of squid giant axons have been studied by means of internal perfusion and voltage clamp techniques. The sample of phospholipases used exhibited both phospholipase A and B activities.2. When applied externally, phospholipases had no effect on the resting and action potentials at a concentration of 100 mug/ml.3. When applied internally, the enzymes effectively suppressed the amplitude and maximum rate of rise of the action potential at a concentration of 100 mug/ml. The resting potential started decreasing appreciably only after the action potential had been suppressed to a considerable extent.4. Under voltage clamp conditions, the peak transient current was suppressed following internal perfusion of phospholipases, 150 mug/ml. The steady-state current began to decrease, and the leakage current to increase only after the transient current had been suppressed to a considerable extent.5. The time course of sodium inactivation was not significantly slowed by internal perfusion of the enzymes.6. The curve relating the peak transient conductance to the membrane potential was shifted in the direction of depolarization after internal perfusion of phospholipases. No appreciable shift of the steady-state conductance curve was observed.7. These experimental results are discussed in connexion with the possible role of membrane phospholipids in the conductance changes associated with excitation.

Action Potentials↗

PubMed1980

Phospholipase B in the brains and meninges of nonsensitized and sensitized rats after challenge with Angiostrongylus cantonensis.

After a primary infection with 100 Angiostrongylus cantonensis larvae, infected rats showed elevated phospholipase B activity in meningeal and brain homogenates beginning with the first week and continuing through the first month of infection. The rise in phospholipase B values through the first 4 weeks, with a prolonged peak spanning days 30 to 31, coincided with the invasion and maturation of the parasites in the brain, and the ensuing sharp decline in phospholipase B levels, shown by the readings on day 45, coincided in turn with the known migration of the worms from the brain to the lungs, which begins about 5 weeks after infection. In the meninges, the pattern of enzyme elevation was generally similar to that in the brain samples except that the highest activity was seen earlier at days 8 to 9, followed by a gradual decline by days 30 to 31 and a sharper drop by day 45. Rats challenged with 100 larvae 53 days after the primary infection exhibited an almost immediate rise of phospholipase B activity in both the brain and meninges; the peaks of activity occurred at day 1 for the meninges and day 25 for the brain, and levels above control values were still present at day 50. Comparison of the total enzymatic content of the cerebral tissue and meninges revealed that a remarkably high proportion of the phospholipase B activity was contained in the meninges. The inference that elevated levels of this enzyme in the cerebral tissue of A. cantonensis-infected rats are due to inflammatory reactions within the meningeal envelopes was confirmed by histochemical demonstration of specific sites of enzymatic activity limited to the meninges. It is of interest that 80% of the cells positive for the enzyme were clearly identifiable as eosinophils since an association of bone marrow eosinophilia and high phospholipase B levels in rats infected with A. cantonensis was shown in our earlier study of rats infected with this parasite.

Angiostrongylus↗

PubMed1998

Phospholipase A of Yersinia enterocolitica contributes to pathogenesis in a mouse model.

Some isolates of Yersinia enterocolitica exhibit phospholipase activity, which has been linked to lecithin-dependent hemolysis (M. Tsubokura, K. Otsoki, I. Shimohira, and H. Yamamoto, Infect. Immun. 25:939-942, 1979). A gene encoding Y. enterocolitica phospholipase was identified, and analysis of the nucleotide sequence revealed two tandemly transcribed open reading frames. The first, yplA, has 74% identity and 85% similarity to the phospholipase A found in Serratia liquefaciens. Though the other, yplB, was less similar to the downstream accessory protein found in S. liquefaciens, the organization in both species is similar. Subsequently, a yplA-null Y. enterocolitica strain, YEDS10, was constructed and demonstrated to be phospholipase negative by plate and spectrophotometric assays. To ascertain whether the phospholipase has a role in pathogenesis, YEDS10 was tested in the mouse model. In experiments with perorally infected BALB/c mice, fewer YEDS10 organisms were recovered from the mesenteric lymph nodes and Peyer's patches (PP) than the parental strain at 3 or 5 days postinfection. Furthermore, bowel tissue and PP infected with YEDS10 appeared to be less inflamed than those infected with the parental strain. When extremely high doses of both the parental and YEDS10 strains were given, similar numbers of viable bacteria were recovered from the PP and mesenteric lymph nodes on day 3. However, the numbers of foci and the extent of inflammation and necrosis within them were noticeably less for YEDS10 compared to the parental strain. Together these findings suggest that Y. enterocolitica produces a phospholipase A which has a role in pathogenesis.

Amino Acid Sequence↗

PubMed1972

Mutant of Escherichia coli K-12 deficient for detergent-resistant phospholipase A.

A mutant deficient for detergent-resistant (DR) phospholipase A was isolated from Escherichia coli K-12. Because the enzyme is membrane-bound and the substrate is a lipid, a special procedure was developed for isolating mutants deficient for the enzyme from agar plates. A sodium dodecyl sulfate (SDS)-sensitive mutant was used as a parental strain for the isolation of DR phospholipase A-deficient mutant. Soft agar containing an unsaturated fatty acid auxotroph and SDS was poured over colonies of the parental strain. The cells were easily solubilized with SDS, and phospholipids were efficiently digested by DR phospholipase A from the colonies on an agar plate. Fatty acids released supported the growth of the indicator bacteria. After the cells of the parent were mutagenized with nitrosoguanidine, colonies which could not support the growth of an unsaturated fatty acid auxotroph in the presence of SDS were selected. Four mutants were isolated after in vitro scre[UNK]ning of DR phospholipase A activity of 30 halo-less clones. Since an extract of the parent strain mixed with that of a mutant strain was still active, it was concluded that the inability to hydrolyze phospholipids was not due to the accumulation of inhibitory substance; the activity of DR phospholipase A in the mutant was less than 1% of the parental activity. Physiological studies indicated that DR phospholipase A is not essential for the growth of E. coli.

Carbon Isotopes↗

PubMed2006

The global regulatory proteins LetA and RpoS control phospholipase A, lysophospholipase A, acyltransferase, and other hydrolytic activities of Legionella pneumophila JR32.

Legionella pneumophila possesses a variety of secreted and cell-associated hydrolytic activities that could be involved in pathogenesis. The activities include phospholipase A, lysophospholipase A, glycerophospholipid:cholesterol acyltransferase, lipase, protease, phosphatase, RNase, and p-nitrophenylphosphorylcholine (p-NPPC) hydrolase. Up to now, there have been no data available on the regulation of the enzymes in L. pneumophila and no data at all concerning the regulation of bacterial phospholipases A. Therefore, we used L. pneumophila mutants in the genes coding for the global regulatory proteins RpoS and LetA to investigate the dependency of hydrolytic activities on a global regulatory network proposed to control important virulence traits in L. pneumophila. Our results show that both L. pneumophila rpoS and letA mutants exhibit on the one hand a dramatic reduction of secreted phospholipase A and glycerophospholipid:cholesterol acyltransferase activities, while on the other hand secreted lysophospholipase A and lipase activities were significantly increased during late logarithmic growth phase. The cell-associated phospholipase A, lysophospholipase A, and p-NPPC hydrolase activities, as well as the secreted protease, phosphatase, and p-NPPC hydrolase activities were significantly decreased in both of the mutant strains. Only cell-associated phosphatase activity was slightly increased. In contrast, RNase activity was not affected. The expression of plaC, coding for a secreted acyltransferase, phospholipase A, and lysophospholipase A, was found to be regulated by LetA and RpoS. In conclusion, our results show that RpoS and LetA affect phospholipase A, lysophospholipase A, acyltransferase, and other hydrolytic activities of L. pneumophila in a similar way, thereby corroborating the existence of the LetA/RpoS regulation cascade.

Acyltransferases↗

PubMed1989

Cardiolipin-sensitive phospholipase C in subcellular fractions of rabbit myocardium.

Phosphatidylinositol-specific phospholipase C was characterized in the soluble phase and in membrane fractions prepared from rabbit myocardium. Four subforms of soluble phospholipase C were identified and characterized. Activity of one subform was inhibited 80% when cardiolipin was present in substrate vesicles, whereas three subforms were stimulated 2- to 10-fold by cardiolipin. A cationic subform, molecular mass 67 kDa, was stimulated threefold when cardiolipin comprised 2% of the total phospholipid and fivefold when it comprised 12%. The major mechanism for the cardiolipin effect was a decrease in the apparent Michaelis constant (Km) of this subform for substrate. Competition experiments were consistent with binding of this subform to cardiolipin. Phospholipase C activity was present in mitochondrial, microsomal, and sarcolemmal membrane fractions that were essentially free of contamination by cytosol. Detection of membrane-associated phospholipase C was facilitated by cardiolipin. Thus rabbit myocardium contains multiple subforms of soluble phospholipase C that differ substantially in surface charge, molecular mass, and sensitivity to cardiolipin. Anionic phospholipids may be important determinants of intracellular distribution of phospholipase C in myocardial tissue.

Animals↗

PubMed1993

Enhanced keratinocyte prostaglandin synthesis after UV injury is due to increased phospholipase activity.

The possibility that increased eicosanoid synthesis in skin after ultraviolet light irradiation is due to enhanced phospholipase activity was examined. [3H]arachidonic acid-labeled human keratinocyte cultures exposed to 30 mJ/cm2 ultraviolet (UV) B were studied 6 h after injury. Bradykinin-stimulated release of [3H]arachidonic acid was increased 1.8-fold over release from control cultures by prior irradiation. In unlabeled cultures, prior irradiation produced a threefold increase in bradykinin-stimulated prostaglandin (PG) E2 synthesis as measured by immunoassay. The relative contribution of increased phospholipase vs. cyclooxygenase activity was therefore examined using stable isotope mass measurements of PGE2. By this method, prior irradiation increased bradykinin-stimulated phospholipase activity 3.5-fold, while no change in total cellular cyclooxygenase activity was observed. The effects of irradiation on phospholipase activity were then assessed in more detail. The activities of phospholipase A2, arachidonoyl-CoA synthetase, and arachidonoyl-CoA lysophosphatide acyltransferase in cell homogenates were determined. No effect of UV exposure on the activity of these enzymes was observed. These results suggest that the increase in prostaglandin synthesis produced after UV irradiation is due to increased phospholipase activity, thus enhancing arachidonate release.

Acylation↗

PubMed1997

Ischemic preconditioning triggers phospholipase D signaling in rat heart.

Recent studies have indicated that repeated brief episodes of ischemia and reperfusion render the myocardium more tolerant to subsequent lethal ischemic injury. In view of the previous observations that ischemia-reperfusion potentiates phospholipase D signaling and that such signaling is beneficial for the heart, we investigated whether a similar phospholipase D signaling is responsible for the beneficial effects associated with repeated ischemia and reperfusion. Using an isolated perfused working rat heart model, we demonstrated that four brief episodes of 5 min of ischemia and 10 min of reperfusion reduced the incidence of ventricular arrhythmias, enhanced the postischemic ventricular performance, and decreased the release of creatine kinase from the reperfused heart, with simultaneous activation of phospholipase D generating the second messengers diacylglycerol and phosphatidic acid and leading to the translocation and activation of protein kinase C. The specific antiphospholipase D antibody blocked the activation of phospholipase D and attenuated the generation of diacylglycerol and phosphatidic acid and activation of protein kinase C. In concert, phospholipase D inhibition increased the incidence of ventricular arrhythmias, blocked the beneficial effects of preconditioning on the ventricular performance, and increased the amount of creatine kinase release from the coronary effluent. The results of this study indicate that repeated brief episodes of ischemia and reperfusion exert beneficial effects on the intact rat heart by triggering the activation of a phospholipase D signaling mechanism.

Animals↗

PubMed2000

Altered cardiac Na(+)/H(+) exchange in phospholipase D-treated sarcolemmal vesicles.

Cardiac sarcolemmal Na(+)/H(+) exchange is critical for the regulation of intracellular pH, and its activity contributes to ischemia-reperfusion injury. It has been suggested that the membrane phospholipid environment does not modulate Na(+)/H(+) exchange. The present study was carried out to determine the effects on Na(+)/H(+) exchange of modifying the endogenous membrane phospholipids through the addition of exogenous phospholipase D. Incubation of 0.825 U of phospholipase D with 1 mg of porcine cardiac sarcolemmal vesicles hydrolyzed 34 +/- 2% of the sarcolemmal phosphatidylcholine and increased phosphatidic acid 10.2 +/- 0.5-fold. Treatment of vesicles with phospholipase D resulted in a 46 +/- 2% inhibition of Na(+)/H(+) exchange. Na(+)/H(+) exchange was measured as a function of reaction time, extravesicular pH, and extravesicular Na(+). All of these parameters of Na(+)/H(+) exchange were inhibited following phospholipase D treatment compared with untreated controls. Passive efflux of Na(+) was unaffected. Treatment of sarcolemmal vesicles with phospholipase C had no effect on Na(+)/H(+) exchange. We conclude that phospholipase D-induced changes in the cardiac sarcolemmal membrane phospholipid environment alter Na(+)/H(+) exchange.

Animals↗