Sequence of deposition of heterogeneous amyloid beta-peptides and APO E in Down syndrome: implications for initial events in amyloid plaque formation

Patients with trisomy 21 [Down syndrome (DS)] progressively develop amyloid beta-protein (A beta) deposits and then other features of Alzheimer's disease (AD), apparently due to increased gene dosage and thus expression of the beta-amyloid precursor protein. Because the neuropathological phenotype in older DS subjects closely resembles that of AD, the examination of DS brains of increasing age provides a unique model of the progression of AD. Here, we characterized the deposition of several A beta peptides and apolipoprotein E in formalin-fixed brain sections from 29 DS subjects between 3 and 73 years old. Amyloid plaque number and the percentage of cortical area they occupied were quantified by computerized image analysis. A beta ending at amino acid 42 (A beta 42) was the earliest form of A beta deposited in DS cortex. It was observed in 7 of 16 young (3-30 years) subjects, with the earliest deposition occurring at age 12. A beta ending at residue 40 (A beta 40) was not detected until approximately age 30, a time when degenerating neurites around A beta immunoreactive (IR) plaques were first observed, and the frequency of A beta 40 IR plaques then rose with age. Even in old (51-73 years) DS subjects, A beta 42 IR plaques were always more abundant than A beta 40 IR plaques. A beta peptides starting at aspartate 1 or pyroglutamate 3 were detected in small subsets of compacted, neuritic plaques beginning around age 30 and rose with age, the latter species always exceeding the former. Thus, the N-termini of the A beta 42 peptides abundantly deposited in very young DS subjects remain unknown. Apo E was detectable in a small subset of A beta 42 IR plaques beginning at age 12 and rose steadily with age; it clearly followed the deposition of A beta. Our analysis of very young DS brains suggests that amyloid plaque formation begins with A beta 42-ending peptides, and the number and percentage of cortical area of A beta 42 plaques increase very little with advancing age, while other heterogeneous A beta species and Apo E progressively accrue onto plaques containing A beta 42.

Muscarinic receptor reserve for inhibition of cAMP accumulation in bovine trachealis cells

In airway smooth muscle, muscarinic agonists inhibit synthesis of adenosine 3',5'-cyclic monophosphate (cAMP). The goal was to characterize the relationship between agonist occupancy of muscarinic receptors and regulation of cAMP for bovine trachealis cells. For intact cells dispersed by enzyme, carbachol maximally inhibited 58 +/- 4% (mean +/- SE, n = 5) of isoproterenol-stimulated cAMP accumulation at low concentrations [log half-maximal effective concentration (EC50) = -8.34 +/- 0.16]. In radioligand binding experiments, carbachol competed for [3H]quinuclidinyl benzilate (n = 7) and [N-methyl-3H]scopolamine (n = 3) binding sites on intact cells with both low (log KL = -4.26 +/- 0.06 and -4.50 +/- 0.20, respectively) and high affinities (log KH = -5.91 +/- 0.24 and -6.39 +/- 0.19, respectively). In separate experiments, a fraction of the muscarinic receptors on intact cells were inactivated with either phenoxybenzamine (POB) or propylbenzylcholine mustard (PBCM). We compared equally effective concentrations of carbachol before and after partial inactivation of receptors, and the calculated equilibrium dissociation constants for agonist (log KA = -4.36 +/- 0.42 to -3.20 +/- 0.40 for POB; log KA = -4.27 +/- 0.45 for PBCM) were much greater than the half-maximally effective concentration of carbachol in control cells (log EC50 = -8.34 +/- 0.16). Based on these equilibrium dissociation constants, we calculated that maximum responses (EC95) to carbachol were obtained by occupancy of 0.8% of the receptors coupled to cAMP regulation. We concluded that muscarinic inhibition of cAMP accumulation is characterized by a muscarinic receptor reserve.

Muscarinic inhibition of adenylyl cyclase regulates intracellular calcium in single airway smooth muscle cells

To determine whether muscarinic agonists attenuated isoproterenol-stimulated decreases in intracellular calcium concentration ([Ca2+]i), changes in [Ca2+]i were measured in single airway smooth muscle cells using ratiometric analysis of fura 2 fluorescence. Isoproterenol (10(-5) M) and 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) decreased [Ca2+]i by 24 +/- 3% (P < 0.05, n= 28) and 17 +/- 1% (P < 0.05, n = 6), respectively. The decreased [Ca2+]i in response to isoproterenol was inhibited by propranolol (10(-6) M) and Rp-adenosine 3',5'-cyclic monophosphothioate (Rp-cAMPS) (10-40 microM). In subsequent experiments assessing the effects of muscarinic agonists, isoproterenol did not decrease [Ca2+]i in the presence of carbachol (5 x 10(-8) M) (6 +/- 8% increase; NS, n = 8). To determine the mechanism underlying this inhibitory effect of carbachol, cells were loaded with 4,5-dimethoxy-2-nitrobenzyl adenosine-3',5'-cyclic monophosphate (caged cAMP). For cells loaded with 20 microM caged cAMP, photolysis of caged cAMP decreased basal [Ca2+]i by 28 +/- 3% (P < 0.05, n = 12). In the presence of carbachol (5 x 10(-8) M), photolysis of caged cAMP still induced a 27 +/- 4% decrease in [Ca2+]i (P < 0.05, n = 12). We concluded that a low concentration of carbachol did attenuate isoproterenol-stimulated decreases in [Ca2+]i. Because low concentrations of carbachol attenuated the decreases in [Ca2+]i stimulated by isoproterenol but not the comparable decreases stimulated by cAMP directly, we concluded that the inhibition of adenylyl cyclase activity by muscarinic agonists contributed to the regulation of [Ca2+]i in airway smooth muscle cells. The findings suggested that physiological levels of cholinergic stimulation inhibit adenylyl cyclase, thereby attenuating the effects that beta-adrenergic agonists have on [Ca2+]i.

[Hansenula anomala fungemia in a patient undergoing IVH-treatment with ascending colon carcinoma]

A case of catheter-related fungemia due to Hansenula anomala is reported. A 61-year-old male was diagnosed as having stage 3 ascending colon carcinoma stenosing the colon severely and was admitted to our hospital to receive an operation of the carcinoma. Just after admission, an intravenous hyperalimentation (IVH) catheter was inserted and IVH was started to prevent development of ileus and to prepare for laparotomy. Nine days later, he developed a fever. On the next day, the IVH catheter was removed and cultures of blood and the catheter revealed the presence of yeast-like organisms that were identified as H. anomala. Laboratory data showed hypogranulocytemia, slight disturbances of liver and kidney, a prolongation of PT, an increase of FDP and positive reaction of candida antigen by CAND-TEC. He improved after the removal of the catheter, and treatment with intravenous infusion of fluconazole 2 days after the removal was thought to be useful for recovery and to prevent the reappearance of infection though susceptibility to fluconazole was not good. Human infections due to H. anomala are rare and this is the 8th case of H. anomala fungemia in Japan. From this report and a review of the literature, risk factors for developing this fungemia include the use and abuse of central venous catheters such as IVH-catheter. It appears that H. anomala has recently emerged as a potential pathogen in the immunocompromised hosts and patients after insertion of central venous catheters and that these organisms should be added to the growing list of unusual fungal pathogens in these patients.

Wound healing effect of the new imidazole antimycotic lanoconazole in rats

The wound healing effect of cream preparations of lanoconazole (CAS 101530-10-3, NND-318), an antimycotic imidazole compound, was examined using an excisional open skin-wound model produced on the back of rats. The rapid decrease in the size of wounded areas showed that 0.5% and 1% lanoconazole creams accelerated spontaneous healing. The effectiveness was almost similar to that of an ointment containing 5% deproteinized calf blood extract (DCBE), a wound healing agent on the market. In contrast, neither 1% clotrimazole cream nor 1% bifonazole cream, both of which are imidazole antimycotics, showed an accelerative effect. The wound healing effect of lanoconazole was further confirmed by histological evaluation; a thicker and more cellular granulation tissue was formed, and epidermal regeneration was more stimulated by lanoconazole than by non-treatment or vehicle alone. The effect of lanoconazole on the formation of granulation tissue in rats was also studied using a cotton pellet implantation method. Lanoconazole accelerated the formation of this tissue in terms of dry weight in a dose dependent manner (0.5-4 mg/pellet), and collagen content and angiogenesis also increased in the stimulated tissue, indicating that these accompany the compound-induced acceleration of tissue formation. These results suggest that lanoconazole has a distinctive wound healing effect which is a feature no other imidazole antimycotic is known to possess to date.

[Reconstruction procedure for full-thickness chest wall defects]

Reconstruction of full-thickness chest wall defects after the total layer resection of the chest wall has been performed on 6 cases. Five of 6 cases had local recurrent of breast carcinoma, one case had a recurrent liposarcoma in the chest wall. The reconstruction procedure of skeletal chest wall used to double soft Marlex mesh. The soft tissue layer of the chest wall was reconstructed with myocutaneous flaps in five cases (four cases using latissimus dorsi, one case using rectus abdominis), with omental pedicle graft and free skin flap in one case. Minor wound complications occurred in 2 in the 6 cases, one case had myocutaneous flap using rectus abdominis, the other case using omental pedicle flap, but any postoperative complications including respiratory insufficiency was not seen with myocutaneous flap using latissimus dorsi. The latissimus dorsi myocutaneous flap was most suitable to cover the soft tissue layer of the chest. We confirmed that Marlex mesh and latissimus dorsi myocutaneous flap were able to reconstructed for large defects of full-thickness chest wall involving the sternum, there were best approach to reconstruction full-thickness chest wall defects after total layer chest wall resection.

[Effect of endothelin on ionic background in the optic nerve head of rabbits]

Endothelin-1 (ET-1) is thought to have some effect on the retinal circulation and its autoregulation. The disturbance of ET-1 secretion might contribute to the pathogenesis of retinochoroidal or optic nerve disease. In this study, to determine the effect of ET-1 on the optic nerve head, we observed the optic nerve with a transmission electron microscope and measured element contents in the axon and myelin of the optic nerve head by electron probe X-ray microanalysis. Albino rabbits were given an injection of 0.1 ml (10(-6)M) ET-1 into the middle of the vitreous of one eye (ETs) and 0.1 ml Opeguard-MA into the other eye (controls), and 2 hours after the injection changes in the optic disc were observed. In transmission electron microscopy (n = 3), axon polymorphism and myelin disorder were seen. The X-ray analysis of frozen sections (n = 5) revealed that with ET-1 treatment Ca and Cl concentrations were increased in the axon, and K concentration was decreased significantly in both axon and myelin. These results suggest that the increase of intracellular Ca could elevate the activity of some proteases, which might then cause damage to the optic nerve.

[Surgical pathology of infective endocarditis]

Underlying pathologic disorders of infected valves were analyzed in 36 consecutive patients with infective endocarditis (from April 1987 to May 1995) of 18 aortic, 11 mitral and 8 prosthetic valves. Among 29 cases of native valve endocarditis, 27 had known organic changes [aortic valve prolapse 8, bicuspid aortic valve 4, annuloaortic ectasia 1, mitral valve prolapse 9 (including 2 cases associated with hypertrophic cardiomyopathy), looping chordae 1, rheumatic heart disease 4]. However, the remaining two cases had unknown etiology. Histological examination of these two aortic valves revealed proliferation of small vessels and remnants of vascular smooth muscle cells, suggesting postinflammatory valve prolapse. Five cases with definite pathology had no clinical signs of infection. The preponderance of surgically resected valves with infective endocarditis in Japan is non-rheumatic in origin.

Role of endogenous cholecystokinin in the regeneration of pancreatic tissue after acute hemorrhagic pancreatitis in rats

The aim of this study was to investigate the effect of endogenous cholecystokinin (CCK) on pancreatic regeneration after acute hemorrhagic pancreatitis. Acute hemorrhagic pancreatitis was induced in rats by two intraperitoneal cerulein injection (20 micrograms/kg BW) with 5h water-immersion stress once a day for successive 3 days. After the cessation of repetition of acute pancreatitis the rats were treated with successive feeding with 0.1% camostat-containing diet or SC injection of CR-1505 (CCK receptor antagonist, 50 mg/kg BW x 2/day) for 7 days. Zymogen enzymes and protein contents per DNA in pancreatic tissue were significantly higher in rats treated with camostat compared with control rats, and plasma CCK level was elevated. To the contrary, pancreatic regeneration was retarded in the rats treated with CR 1505. It is concluded that endogenous CCK has a trophic effect during regeneration after acute hemorrhagic pancreatitis.

Common antigenicity between Yersinia enterocolitica-derived heat-shock protein and the retina, and its role in uveitis

Yersinia enterocolitica-derived heat-shock protein (HSP60) was recently demonstrated to be associated with certain systemic autoimmune diseases. A role for HSP60 is also suspected in the pathogenesis of some types of uveitis believed to involve autoimmune mechanisms, such as Behçet's disease. We report our results on the role of HSP60 in patients with uveitis. HSP60 was subjected to electrophoresis in immunoblot analysis, and then allowed to react with sera from patients with uveitis in order to detect the presence of anti-HSP60 antibody. Tissue extracts from human and bovine retina were also electrophoresed, and then treated with anti-HSP60 monoclonal antibodies to determine whether or not the antibodies recognized ocular tissues. Immunoblot analysis revealed anti-HSP60 antibodies in patient sera. Furthermore, anti-HSP60 monoclonal antibodies reacted against the 60-kD protein derived from human and bovine retinal extracts. These immunological cross-reactions between HSP60 and the retina demonstrate a common antigenicity. Furthermore, detection of specific antibody against HSP60 in patient sera suggests that this common antigenicity between HSP60 and the retina may be related to the pathogenesis of uveoretinitis in some cases.

Analysis of of the epitopes recognized by mouse monoclonal antibodies directed to Yersinia enterocolitica heat-shock protein 60

To determine amino acid sequences of the epitopes recognized by monoclonal antibodies (mAbs) 3C8 and 5C3 directed against Yersinia enterocolitica heat-shock protein (HSP60), a dot blot analysis was performed using synthesized peptides of Y. enterocolitica HSP60 such as peptides p316-342, p327-359, p340-366, p316-326, p316-321, p319-323, and p321-326 which represent positions of amino acids in Y. enterocolitica HSP60. The dot blot analysis revealed that 5C3 mAb reacted with p316-342, p316-326 and p321-326, and 3C8 mAb p316-342 and p316-326. These results indicate that the epitopes recognized by the mAbs were associated with eleven amino acids, Asp Leu Gly Gln Ala Lys Arg Val Val Ile Asn, of p316-326. The sequence homology between p316-326 of Y. enterocolitica HSP60 and the rest of the HSP60 family suggests that the five amino acids of Lys, Arg, Val, Ile and Asn, which are highly conserved in the HSP60 family, might be related with the epitope recognized by 3C8. In contrast, it was also demonstrated that three amino acids of Leu, Gly and Val, which are not well conserved in the HSP60 family, might be related to the epitope recognized by 5C3.

Theoretical analysis of magnetic field interactions with aortic blood flow

The flow of blood in the presence of a magnetic field gives rise to induced voltages in the major arteries of the central circulatory system. Under certain simplifying conditions, such as the assumption that the length of major arteries (e.g., the aorta) is infinite and that the vessel walls are not electrically conductive, the distribution of induced voltages and currents within these blood vessels can be calculated with reasonable precision. However, the propagation of magnetically induced voltages and currents from the aorta into neighboring tissue structures such as the sinuatrial node of the heart has not been previously determined by any experimental or theoretical technique. In the analysis presented in this paper, a solution of the complete Navier-Stokes equation was obtained by the finite element technique for blood flow through the ascending and descending aortic vessels in the presence of a uniform static magnetic field. Spatial distributions of the magnetically induced voltage and current were obtained for the aortic vessel and surrounding tissues under the assumption that the wall of the aorta is electrically conductive. Results are presented for the calculated values of magnetically induced voltages and current densities in the aorta and surrounding tissue structures, including the sinuatrial node, and for their field-strength dependence. In addition, an analysis is presented of magnetohydrodynamic interactions that lead to a small reduction of blood volume flow at high field levels above approximately 10 tesla (T). Quantitative results are presented on the offsetting effects of oppositely directed blood flows in the ascending and descending aortic segments, and a quantitative estimate is made of the effects of assuming an infinite vs. a finite length of the aortic vessel in calculating the magnetically induced voltage and current density distribution in tissue.

Genotype frequencies of the human platelet antigen, Ca/Tu, in Japanese, determined by a PCR-RFLP method

Recently, the polymorphism of a new human platelet antigen, Ca/Tu, was shown to be derived from a G-A nucleotide substitution at base 1564 of GPIIIa cDNA, which leads to a single amino acid difference, Arg/Gln at amino acid 489 of GPIIIa. We developed a PCR-RFLP method to determine the genotypes of Ca/Tu and their frequencies in a Japanese population. Fifteen Ca/Tua donors comprising 1 Ca/Tu(a/a) homozygous donor and 14 Ca/Tu(a/b) heterozygous donors were found among the 314 random donors analyzed. The frequencies of Ca/Tu genes were 0.025 (Ca/Tua) and 0.975 (Ca/Tu(b)). The present study showed that the frequency of Ca/Tua individuals in the Japanese (15/314) was approximately 7-fold higher than in the Finnish population (1/150) previously reported by Kekomäki et al. Therefore, attention must be given to the involvement of the Ca/Tu alloantigen in neonatal alloimmune thrombocytopenia and the refractoriness of platelet transfusion.

Amyloid beta protein in rat soleus muscle in chloroquine-induced myopathy using end-specific antibodies for A beta 40 and A beta 42: immunohistochemical evidence for amyloid beta protein

Previous immunohistochemical studies from this laboratory demonstrated that monoclonal antibodies raised against various regions of amyloid precursor protein (APP) (i.e., N-terminus, amyloid beta protein (A beta), and C-terminus) strongly labeled vacuoles in chloroquine-induced myopathy-affected muscle in rats. In this study, we used antibodies end specific for the A beta 40 and A beta 42 species, and a monoclonal antibody to A beta 1-9 which reacts with APP and A beta. Most vacuoles clearly reacted with anti-A beta 1-9, while about half reacted with anti-A beta 42, and only a few reacted with anti-A beta 40. These results demonstrate that vacuoles in chloroquine-induced myopathy-affected muscle contain cleaved A beta, and that distribution of the two major A beta species is similar to what is observed in A beta deposition in Alzheimer's disease (AD)-affected brain. This provides further evidence that chloroquine-induced myopathy in rats provides a suitable model to understand APP processing into A beta, and the role of APP in terms of the pathogenesis of AD.

The comparison of epidural fentanyl, epidural lidocaine, and intravenous fentanyl in patients undergoing gastrectomy

This study was conducted prospectively to compare the effect of epidural fentanyl (EP-F), epidural lidocaine (EP-L), and intravenous fentanyl (IV-F) on hemodynamic and hormonal responses to surgery and postoperative analgesic requirement in 30 patients undergoing gastrectomy during isoflurane anesthesia. An epidural catheter was placed via the T8-9 interspace. Group EP-F received fentanyl 2 micrograms/kg in 10 mL saline, and Group EP-L, 10 mL 1.5% lidocaine, epidurally; Group IV-F was given fentanyl, 2 micrograms/kg, IV. Fifty percent of the original dose was repeated every hour. Hemodynamic data and plasma hormonal levels were compared between those before and those at 1 h after skin incision. The total number of analgesic administrations within the first 48 h postoperatively were compared. Group EP-L developed more frequent episodes of hypotension. Group IV-F required higher isoflurane concentrations and the plasma epinephrine levels increased more than in Groups EP-F and EP-L. In Groups EP-L and IV-F, the plasma antidiuretic hormone (ADH) level increased more than in Group EP-F. In Groups EP-F and IV-F, the plasma cortisol and adrenocorticotropic hormone (ACTH) levels increased more than in Group EP-L. The use of postoperative analgesics was significantly less in Group EP-F. In conclusion, in Group EP-F, attenuated hormonal responses to surgery was accompanied with less hypotension and postoperative analgesic requirements were reduced.

Changes in apolipoproteins during the acute phase of Kawasaki disease

To determine disturbances of lipid metabolism in patients with Kawasaki disease, we investigated changes in the serum levels of apolipoproteins and serum lipids. Results were as follows. Total serum cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C) decreased during the early stage of Kawasaki disease. The apo A-I and A-II levels were low until the 2nd week of illness. Apo B decreased during the 1st week of illness, but rose slightly during the 2nd and 3rd weeks. The apo B/apo A-I ratio and the apo B/TC ratio were high in the early stages of illness. The group of patients with coronary artery lesions showed low levels of TC and HDL-C, and low levels of apo A-I, A-II and B during the early stages, compared with the group without coronary artery lesions. The apo B/TC ratio was significantly higher in the patients with coronary artery lesions during the 2nd week of illness. Our findings suggest an association between changes in serum lipids and apolipoproteins and coronary artery involvement in Kawasaki disease. These abnormalities may indicate the presence of early coronary arteriosclerosis.

Thermostable peroxidase activity with a recombinant antibody L chain-porphyrin Fe(III) complex

In order to engineer a new type of catalytic antibody, we attempt to use a monoclonal antibody L chain as a host protein for a porphyrin. TCPP (meso-tetrakis(4-carboxyphenyl)porphyine) was chemically synthesized and Balb/c mice were immunized using TCPP as a hapten. Two hybridoma cells (03-1, 13-1), that produce monoclonal antibody against TCPP, were obtained. Genes for both H and L chains of monoclonal antibodies were cloned, sequenced and overexpressed using E. coli as a host. ELISA and fluorescence quenching method show that the independent antibody L chains from both Mab03-1 and Mab13-1 have specific interaction with TCPP. Furthermore, the recombinant antibody L chain from Mab13-1 exhibits much higher peroxidase activity than TCPP Fe(III) alone. The enzyme activity was detectable with pyrogallol and ABTS (2,2-azinobis-3-ethylbenzthiazolin-6-sulfonic acid) but not with catechol. This new catalytic antibody was extremely thermostable. Optimum temperature of the peroxidase reaction by the complex of 13-1L chain and TCPP Fe(III) was 90 degrees C, while that the TCPP Fe(III) alone was 60 degrees C.

Changes in oral functions and posture at rest following surgical orthodontic treatment and myofunctional therapy. Evaluation by means of video recording

Fifteen adult patients with skeletal mandibular prognathism or openbite underwent surgical and orthodontic treatment, then received myofunctional therapy. Cephalograms, facial photographs and oral models were taken on each patient. Patients were then videotaped, frontally and laterally. Observations were made of forty different oral behaviors and oral rest posture. Changes in morphology, speech, and swallowing are described and evaluated.

Flow cytometric analysis using lipophilic dye PKH-2 for adhesion of Vibrio cholerae to Intestine 407 cells

A comparative study of indirect and direct flow cytometric analysis for adherence of Vibrio cholerae to Intestine 407 cells was performed. The direct flow cytometric analysis employed the lipophilic dye PKH-2. It was concluded that direct flow cytometry using the lipophilic dye PKH-2 is useful and convenient for analyzing bacterium-host cell interactions, since it does not require any specific antibody as the first antibody.

Synthesis of novel oligosaccharides from leucrose by an alpha-glucosidase

An alpha-glucosidase was purified in an electrophoretically pure state from an extract of koji culture of Aspergillus sp. KT-11. This enzyme was found to have a transferring activity when the reaction was done in a high concentration of leucrose at pH 4.5. Two kinds of transfer products, fractions I and II, were obtained from leucrose by the enzyme and they were identified as [(alpha-D-glucopyranosyl-(1-->6)-alpha-D-glucopyranosyl-(1-->6)-alpha-D- glucopyranosyl-(1-->5)-D-fructopyranose] and [alpha-D-glucopyranosyl-(1-->6)-alpha-D-glucopyranosyl-(1-->5)-D- fructopyranose], respectively. These are considered to be novel oligosaccharides.

Myocardial recovery during post-ischemic reperfusion: optimal concentrations of Na+ and Ca2+ in the reperfusate and protective effects of amiloride added to cardioplegic solution

The effects of Na+ and Ca2+ concentrations in the reperfusate on post-ischemic myocardial recovery were examined. Also, the myocardial protective effects of amiloride, an inhibitor of the Na+/Ca2+ and Na+/H+ exchange systems, added to cardioplegic solutions were assessed, using an isolated working rat heart perfusion system. Global myocardial ischemia was induced by 30-min normothermic cardioplegic arrest, using St. Thomas' solution. The concentration of Na+ in the reperfusate varied, stepwise, from 75 to 145 mM/l, and that of Ca2+, from 0.1 to 2.5 mM/l. In this study post-ischemic functional recovery was best at 110mM/l Na+ and 1.2-1.8 mM/l Ca2+ in the reperfusate. A significantly greater post-ischemic functional recovery and a lower creatine kinase release were observed when amiloride was added to the cardioplegic solution. Ca2+ overload via Na+/Ca2+ and Na+/H+ exchange systems would, thus, appear to be due, at least in part, to post-ischemic reperfusion injury.