Distinguishing between the catalytic potential and apparent expression of tyrosinase activities

Assays were developed to investigate the catalytic potential and apparent expression of tyrosinase activities. Tyrosine hydroxylase activity determined with cell lysates (in vitro), entire fixed cells (postfixation), or intact living cells (in situ), and 3,4-dihydroxyphenylalanine oxidase assayed spectrophotometrically or by 3,4-dihydroxyphenylalanine staining on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, demonstrated the following results: 1) The in situ assay displayed reduced tyrosine hydroxylase activity in all three tyrosinase-positive oculocutaneous albino (OCA) lines except for Chediak-Higashi Syndrome melanocytes, which displayed normal activity; 2) The in vitro assay had comparable activity of tyrosinase-positive OCA melanocytes as controls, except for one tyrosinase-positive OCA cell line, which demonstrated increased activity; 3) The postfixation assay, compared with the in situ assay, had elevated activity (ie. normalization) of tyrosinase in OCA cells but reduced activity in controls; 4) The spectrophotometric assay for 3,4-dihydroxyphenylalanine oxidase activity correlated very well with the tyrosine hydroxylase activity determined by the in vitro assay; 5) sodium dodecyl sulfate-polyacrylamide gel electrophoresis of melanocyte lysates either stained with 3,4-dihydroxyphenylalanine or immunoblotted with anti-tyrosinase detected abnormal tyrosinase bands in the Chediak-Higashi Syndrome and one line of tyrosinase positive OCA melanocytes, and both lines had release of tyrosinase into the growth media. In conclusion, the selection and combination of these tyrosinase assays would be informative for differentiation and characterization of human albinism.

[Modified en bloc resection procedure for malignant tumor of the shoulder girdle]

En bloc resection of the shoulder girdle (Tikhoff-Linberg procedure) is a valuable limb-sparing surgical technique for bony and soft tissue malignant tumor in and around the proximal humerus and shoulder girdle. Significant amount of hand-elbow function is maintained with the procedure, and long time results in the treatment of neoplasms by this technique was found to be the same as by the method of a forequarter amputation or the shoulder disarticulation in the English literature. Four cases with malignant tumor in the shoulder girdle was treated with this modified method in our department. The average follow-up was 8 years. One case died due to another kind of tumor 6 years after operation, and other 3 cases are alive and disease free.

Plasma renin activity and insulin sensitivity in normotensive subjects

Insulin sensitivity in essential hypertension and atherosclerosis has elicited substantial research interest. Hyperinsulinemia in prospective studies identifies patients at risk for the development of coronary atherosclerosis. Plasma renin activity has also been shown to predict myocardial infarction, and correlates inversely with insulin sensitivity in hypertensive patients. The current study investigated the relationship between plasma renin activity and insulin sensitivity in 25 normotensive subjects. Using the euglycemic clamp technique, the data show a significant inverse correlation between supine plasma renin activity and insulin-mediated glucose uptake (r = -0.44; P = .027). Significant relationships were also found between plasma renin activity and fasting insulin concentration and fasting serum triglycerides. Reductions in relative skeletal muscle blood flow during insulin infusion have been reported in insulin-resistant compared to insulin-sensitive subjects. Skeletal muscle is the main site of insulin action during euglycemic clamp study and angiotensin II increases skeletal muscle blood flow. Increasing plasma renin activity may reflect a metabolic compensation which offsets the relative reduction in insulin-mediated enhancement in skeletal muscle blood flow in insulin resistance by generation of angiotensin II, which in turn promotes skeletal muscle blood flow.

A tyrosine-based motif in the cytoplasmic domain of the alphavirus envelope protein is essential for budding

The budding of enveloped viruses from cellular membranes is believed to be dependent on the specific interaction between transmembrane spike proteins and cytoplasmic core components of the virus. We found that the cytoplasmic domain of the E2 transmembrane spike glycoprotein of Semliki Forest virus contains two essential determinants which are absolutely needed for budding. The first constitutes a single tyrosine residue in the context of a direct pentapeptide repeat. The tyrosine could only partially be substituted for other residues with aromatic or bulky hydrophobic side chains, although these immediately reverted to the original genotype. The second determinant involves palmitylated cysteine residues flanking the tyrosine repeat motif. The function of these is probably to anchor the tail against the inner surface of the membrane so that the tyrosine-containing motif is properly presented to the nucleocapsid. This is the first example where a membrane virus employs a tyrosine signal for the selective incorporation of spike proteins into budding structures.

Application of internal fixation in the treatment for tuberculosis of the spine

This is a study of 18 patients who had surgical treatment for spinal tuberculosis. All patients were admitted with the spinal tuberculosis and treated with a combination of anterior debridement and bone graft with posterior internal fixation using the Luque or Dick technique. The patients were able to walk within a few days postoperation. Three to seven years follow-ups show no recurrence, kyphosis and/or solid fusion.

Transport and interaction of nitrogen oxides and NO2 with CO2-HCO3- transporters in pancreatic acini

Recently, we showed that NO2- increases gap junction (GJ) permeability and synchronizes intracellular Ca2+ concentration oscillations in pancreatic acini (Loessburg et al., J. Biol. Chem. 268: 19769-19775, 1993). NO2- is also an end product of nitric oxide (NO) production and metabolism. Because of the effect of NO2- on GJ permeability and the possible importance of NO2- in NO metabolism and cytotoxicity, we used pancreatic acinar cells and intracellular pH (pHi) measurements to study the interaction of nitrogen oxides and NO2- with cellular proteins. Exposing cells to NO2- resulted in a concentration-dependent cytosolic acidification. The acidification did not require the transport of NO2- and was not mediated by diffusion of HNO2. Because the acidification was prevented by CO2-HCO3- and inhibition of carbonic anhydrase, it is possible that other nitrogen oxides present in a solution containing NO2- enter the cells by diffusion and interact with OH- or H2O to stably acidify the cytosol. NO2- itself is shown to be transported by the HCO3- transporters present in the plasma membrane. Thus manipulation of the cellular Cl- gradient and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) were used to show Cl-/NO2- exchange, whereas stimulation of external Na(+)-dependent amiloride-insensitive and DIDS-sensitive pHi increase in acidified cells was used to demonstrate a Na(+)-(NO2-)n cotransport. Hence NO2- can be a convenient substitute for HCO3- when studying HCO3- transport in an open system. The studies also show that cellular levels of nitrogen oxides and NO2- can be modulated by the cellular HCO3(-)-buffering system.(ABSTRACT TRUNCATED AT 250 WORDS)

Oligomerization of an avian thymic parvalbumin. Chemical evidence for a Ca(2+)-specific conformation

CPV3, the third parvalbumin isoform to be identified in the chicken, is produced exclusively in the thymus gland. Although parvalbumins are typically cysteine-deficient, CPV3 contains two cysteine residues, at positions 18 and 72. The reported three-dimensional parvalbumin structures suggest that the side chain of cysteine-72 should be solvent-accessible. Accordingly, we find that CPV3 readily forms disulfide-linked oligomers in the absence of reducing agents. The reaction, employing either O2 or ferricyanide ion as the oxidant, is apparently restricted to the Ca(2+)-bound form of the protein. The differing reactivity of the Ca2+, Mg2+, and apo-forms has significant structural implications.

Phase-unwrapping algorithm for the measurement of three-dimensional object shapes

A new phase-unwrapping algorithm is described that uses two phase images with different precision in the unwrapping; this technique can produce an approximately correct unwrapping in the presence of discontinuities. We introduce it into the measurement of a three-dimensional object shape and also present the experimental results.

On the analysis of the pathophysiology of Chediak-Higashi syndrome. Defects expressed by cultured melanocytes

BACKGROUND

The Chediak-Higashi syndrome (CHS) is a disorder that affects the synthesis and/or maintenance of storage/secretory granules in various types of cells. Lysosomes of leukocytes and fibroblasts, dense bodies of platelets, azurophilic granules of neutrophils and melanosomes of melanocytes are generally larger in size and irregular in morphology, indicating that a common pathway in storage organellogenesis is affected in patients with CHS.

EXPERIMENTAL DESIGN

A pure line of melanocytes has been established using a 2 cm2 shave biopsy from a child with CHS. This 4-week-old male patient had oculocutaneous albinism and expressed neutropenia, impaired platelet function, and no natural killer cell activity. The cultured CHS melanocytes were analyzed for cell biological and biochemical aberrancies.

RESULTS

Cultured melanocytes demonstrated some large and/or complexed melanosomes that resembled those observed in melanocytes from ultrastructural sections of the biopsy. Cytoplasmic localization of tyrosinase, tyrosinase-related protein-1 and granulophysin (a 40 kilodalton membrane protein originally identified as a component in dense bodies of platelets) demonstrated a prominent perinuclear accumulation. The basal synthesis of melanin and the activity levels of tyrosine hydroxylase, dihydroxyphenylalanine (DOPA) oxidase, or DOPAchrome tautomerase were comparable to control Caucasian melanocytes in culture. However, melanin synthesis as well as the catalytic activities of tyrosinase were not dramatically upregulated in CHS melanocytes by the addition of isobutyl methylxanthine and cholera toxin in the growth medium when parameters were assayed in cell lysates. In contrast, when assays were performed using live cells, tyrosine hydroxylase demonstrated dramatic upregulation. Medium conditioned by CHS melanocytes demonstrated phenylthiourea-inhibitable tyrosinase activity. Melanocyte lysates and conditioned medium analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and DOPA staining showed an extra, approximately 100 kilodalton soluble protein band with DOPA positivity and tyrosinase immunoreactivity. In addition to tyrosinase, one of three lysosomal enzymes assayed (beta-glucuronidase) was aberrantly secreted into the medium.

CONCLUSIONS

These results demonstrate that melanocytes cultured from CHS express a defect in the structure and/or function of the melanosome and abnormal trafficking of some cellular proteins.

Membrane localization of H+ and HCO3- transporters in the rat pancreatic duct

The pancreatic duct secretes alkaline fluid that is rich in HCO3- and poor in Cl-. The molecular mechanisms that mediate ductal secretion and are responsible for the axial gradients of Cl- and HCO3- along the ductal tree are not well understood because H+ and HCO3- transport by duct cells have not been characterized or localized. To address these questions, we microdissected the intralobular, main, and common segments of the rat pancreatic duct. H+ and HCO3- transporters were characterized and localized by following intracellular pH while perfusing the bath and the lumen of the ducts. In intralobular ducts, Na(+)-dependent and amiloride-sensitive recovery from acid load in the absence of HCO3- was used to localize a Na+/H+ exchanger to the basolateral membrane (BLM). Modification of Cl- gradients across the luminal (LM) and BLM in the presence of HCO3- showed the presence of Cl-/HCO3- exchangers on both membranes of intralobular duct cells. Measurement of the effect of Cl- on one side of the membrane on the rate and extent of pHi changes caused by removal and addition of Cl- to the opposite side suggested that both exchangers are present in the same cell. In the presence of HCO3-, intralobular duct cells used three separate mechanisms to extrude H+: (a) BLM-located Na+/H+ exchange, (b) Na(+)-independent vacuolar-type H+ pump, and (c) BLM-located, Na(+)-dependent, amiloride-insensitive, and 4',4'-diisothiocyanatostilbene-2,2'-disulfonic acid sensitive mechanism, possibly a Na(+)-dependent HCO3- transporter. The main and common segments of the duct displayed similar mechanisms and localization of H+ and HCO3- transporters to the extent studied in the present work. In addition to the transporters found in intralobular ducts, the main and common ducts showed Na+/H+ exchange activity in the LM. Three tests were used to exclude a significant luminal to basolateral Na+ leak as the cause for an apparent luminal Na+/H+ exchange in an HCO3- secreting cells: (a) addition of amiloride and removal of Na+ from the LM had a profound effect on Na+/H+ exchange activity on the BLM and vice versa; (b) inhibition of all transporters in the BLM by bathing the duct in the inert hydrocarbon Fluorinert FC-75 did not prevent cytosolic acidification caused by removal of luminal Na+; and (c) luminal Na+ did not activate the basolateral Na(+)-dependent HCO3- transporter. An Na(+)-independent, bafilomycin-sensitive H+ pumping activity was marginal in the absence of HCO3-.(ABSTRACT TRUNCATED AT 400 WORDS)

TGF-beta 1 gene expression in cultured human keratinocytes does not decrease with biologic age

The biologic activity of cultured epithelial grafts is believed to diminish with increasing cellular age. Therefore, keratinocytes from young donors are used preferentially in the production of cultured allografts for wound treatment. However, the impact of biologic age on cytokine gene expression by human keratinocytes has not been previously investigated. In this study, transforming growth factor-beta 1 (TGF-beta 1) gene expression in human keratinocytes derived from normal foreskins of males ranging in age from 7 months to 82 years was analyzed. Keratinocytes were harvested from fresh specimens and cultivated in vitro on 3T3 fibroblast feeder layers through second passage. The cells were analyzed both qualitatively and semiquantitatively for TGF-beta 1 gene expression using three separate techniques: in situ hybridization, Northern hybridization, and competitive polymerase chain reaction. By in situ hybridization, the signal representing TGF-beta 1 transcript was detected in cells in all layers of the stratified cultures, and immunohistochemical staining for TGF-beta 1 protein was equally intense in all layers. Northern blots of total RNA extracted from the cultivated cells showed no decrease in band density with increasing biologic age. Likewise, no decrease in TGF-beta 1 mRNA levels with biologic age was observed using a semiquantitative polymerase chain reaction assay. These results indicate that the potential for TGF-beta 1 gene expression in cultured foreskin keratinocytes does not decline with increasing cellular age. The findings imply that the clinical performance of cultured grafts, at least as it relates to the elaboration of this growth factor, may not be significantly altered by the biologic age of the keratinocyte donor.

[The use of internal fixation in the treatment of spinal tuberculosis]

We have applied debridement with grafting and internal fixation techniques (including Luque and Dick procedures) in the treatment of tuberculosis of the spine in the past few years. Analysis of 18 patients showed good prognosis after the Luque or Dick procedure. The patients are able to walk around within a few days after operation. One to five years of follow-up showed no recurrence or kyphotic deformity.

Radiofrequency current catheter ablation of the left atrioventricular accessory pathways with paroxysmal supraventricular tachycardia

Seventy patients with left atrioventricular accessory pathways and paroxysmal supraventricular tachycardia (PSVT) underwent radiofrequency catheter ablation (RFCA). The success rate was 94.3%. Among these patients, 26 had manifest preexcitation syndrome, and 44 had concealed preexcitation. Eighteen patients with concealed preexcitation underwent coronary sinus (CS) pacing, and delta wave appeared in 15. The keys to successful RFCA were correct positioning of the radiofrequency (RF) catheter tip, A/V amplitude ratio, AV interval (in sinus rhythm) and VA interval (during SVT or ventricular pacing). After 1-14 months of follow-up, two patients had supraventricular tachycardia (SVT) recurrence.

Human TRP-1 has tyrosine hydroxylase but no dopa oxidase activity

Human TRP-1 has been immunopurified from normal human melanocytes cultured from black neonatal subjects and used to investigate the catalytic function of TRP-1 for the two substrates, L-tyrosine and L-DOPA. Immunopurified TRP-1 did not demonstrate DOPA staining on SDS/PAGE nor DOPA oxidase (DO) activity with either routine or modified assays. The purified TRP-1 also demonstrated no tyrosine hydroxylase (TH) activity using the routine Pomerantz assay. However, there was apparent TH activity exhibited by immunopurified TRP-1 under conditions with low tyrosine concentration (< or = 0.8 microCi/ml of 3H-tyrosine), prolonged incubation time (i.e., overnight) and in the absence of the cofactor L-DOPA. Using these latter specific conditions, TH activity was also detected in cell lysates from a tyrosinase-negative albino melanocyte line which exhibited no TH activity with the routine Pomerantz assay. In addition, TH activity under low substrate assay conditions was not exhibited in a melanocyte line derived from a TRP-1 deficient, Brown albino individual. However, the absence of TH in this Brown albino cell line could be compensated for by the addition of L-DOPA to the assay. These results suggested that TRP-1 has some tyrosine hydroxylase but no DOPA oxidase activity. We propose that one function of TRP-1 is to modulate tyrosinase activity by making DOPA available as a cofactor to perpetuate the initial steps in melanogenesis.

The activity of parafusin is distinct from that of phosphoglucomutase in the unicellular eukaryote Paramecium

In this paper we identified the presence of a Paramecium phosphoglucomutase enzymatic activity which is clearly distinct from that of parafusin-the exocytosis-related phosphoglycoprotein. Since the recently cloned parafusin showed homology to rabbit muscle phosphoglucomutase, we have designed a specific peptide parafusin antibody-generated to a region not present in any known sequenced phosphoglucomutases-to distinguish parafusin from the Paramecium phosphoglucomutase. Separation of these two proteins was obtained using liquid chromatography, enzymatic activity assay and immunoblotting analysis with the specific parafusin peptide antibody. Parafusin fractions incorporated [B35S]UDP-Glc but not [35S]Glc-1-P whereas Paramecium phosphoglucomutase fractions incorporated [35S]Glc-1-P but not [B35S]UDP-Glc. This indicates that these two proteins are separate entities exhibiting different properties and most likely distinct functions in the cell.

[The diagnosis and surgical treatment of Leriches syndrome: an analysis of 16 cases]

The authors report 16 cases of atherosclerotic obliteration of the terminal abdominal aorta seen in the period of 1987-1991. Early diagnosis can be made by using color doppler, and angiography and DSA are very important to determinate the clinical patterns and occlusive locations. A/B Index is also valuable in the diagnosis and treatment. Clinically, it should be differentiated from orthopedic, neurologic and urologic diseases, surgical procedure varies with occlusive location, clinical patterns, general status, and conditions of the affected blood vessels. Follow-up found that Y type aorto-femoral bypass get the best result with one-year unobstructed rate of 100% in all cases, and five-year cumulative unobstructed rate of 75%. The outcome of auxiliary-femoral bypass grafts were the least satisfactory, with the five-year cumulative unobstructed rate of only 34%. Comprehensive therapy should be adopted to improve the long-term cumulative unobstructed rate.

Novel avian thymic parvalbumin displays high degree of sequence homology to oncomodulin

CPV3 is a novel avian parvalbumin. It displays an isoelectric point of 4.6, intermediate between that of avian thymic hormone (pI = 4.3) and the muscle parvalbumin isoform (pI = 5.2). Expression of CPV3, like that of avian thymic hormone (ATH), is restricted to the thymic stroma. However, the CPV3 content of chicken thymus tissue (120 micrograms/g tissue) is 4 times lower than that of ATH (500 micrograms/g tissue). The polymerase chain reaction (PCR) was used to gain access to the nucleotide sequence of CPV3. A 147-base pair fragment of the coding sequence, corresponding to residues 48-97, was amplified from total chicken cDNA using degenerate PCR primers. A RACE-PCR strategy was then used to extend the known sequence in both the 5' and 3' directions. The cDNA sequence thus obtained includes 671 base pairs. Primer extension analysis suggests that the cloned cDNA corresponds to a full-length transcript. Northern analysis of chicken mRNA indicates that the average CPV3 transcript is approximately 800 nucleotides in length, significantly smaller than the ATH message (approximately 1000 nucleotides). Southern analysis suggests the presence of a single CPV3 gene in the chicken genome. The translated nucleotide sequence, displaying 108 residues between the initiator and termination codons, is that of a beta-parvalbumin. The CPV3 sequence exhibits 58% identity with ATH and 52% identity with the chicken muscle isoform. Interestingly, CPV3 and the mammalian oncodevelopmental parvalbumin called oncomodulin are identical at 73 of 108 residues (68% identity). Correspondingly, flow-dialysis measurements with 45Ca2+ indicate that the Ca(2+)-binding domains are inequivalent, as in oncomodulin. The apparent dissociation constants, at pH 7.4 in 150 mM NaCl, are approximately 10 nM and 80 nM.

Assembly and entry mechanisms of Semliki Forest virus

The alphavirus Semliki Forest (SFV) is an enveloped virus with a positive single-stranded RNA genome. The genome is complexed with 240 copies of a capsid protein into a nucleocapsid structure. In the membrane the virus carries an equal number of copies of a membrane protein heterodimer. The latter oligomers are grouped into clusters of three. These structures form the spikes of the virus and carry its entry functions, that is receptor binding and membrane fusion activity. The membrane protein heterodimer is synthesized as a p62E1 precursor protein which upon transport to the cell surface is cleaved into the mature E2E1 form. Recent studies have given much new information on the assembly and entry mechanism of this simple RNA virus. Much of this work has been possible through the construction of a complete cDNA clone of the SFV genome which can be used for in vitro transcription of infectious RNA. One important finding has been to show that a spike deletion variant and a capsid protein deletion variant are budding-negative when expressed separately but can easily complement each other when transfected into the same cell. This shows clearly that enveloped viruses use different budding strategies: one which depends on a nucleocapsid-spike interaction as exemplified by SFV and another one which is based on a direct core-lipid bilayer interaction as shown before to be the case with retroviruses. Another important finding concerns the activation process of the presumed fusion protein of SFV, the E1 subunit. In the original p62E1 heterodimer E1 is completely inactive. Activation proceeds in several steps. First p62 cleavage activates the potential for low pH inducible fusion. Next the low pH which surrounds incoming virus in endosomes induces dissociation of the heterodimeric structure. This is followed by a rearrangement of E1 subunits into homotrimers which are fusion active.

Evolution of an enzyme activity: crystallographic structure at 2-A resolution of cephalosporinase from the ampC gene of Enterobacter cloacae P99 and comparison with a class A penicillinase

The structure of the class C ampC beta-lactamase (cephalosporinase) from Enterobacter cloacae strain P99 has been established by x-ray crystallography to 2-A resolution and compared to a class A beta-lactamase (penicillinase) structure. The binding site for beta-lactam (penicillinase) structure. The binding site for beta-lactam antibiotics is generally more open than that in penicillinases, in agreement with the ability of the class C beta-lactamases to better bind third-generation cephalosporins. Four corresponding catalytic residues (Ser-64/70, Lys-67/73, Lys-315/234, and Tyr-150/Ser-130 in class C/A) lie in equivalent positions within 0.4 A. Significant differences in positions and accessibilities of Arg-349/244 may explain the inability of clavulanate-type inhibitors to effectively inactivate the class C beta-lactamases. Glu-166, required for deacylation of the beta-lactamoyl intermediate in class A penicillinases, has no counterpart in this cephalosporinase; the nearest candidate, Asp-217, is 10 A from the reactive Ser-64. A comparison of overall tertiary folding shows that the cephalosporinase, more than the penicillinase, is broadly similar to the ancestral beta-lactam-inhibited enzymes of bacterial cell wall synthesis. On this basis, it is proposed that the cephalosporinase is the older of the two beta-lactamases, and, therefore, that a local refolding in the active site, rather than a simple point mutation, was required for the primordial class C beta-lactamase to evolve to the class A beta-lactamase having an improved ability to catalyze the deacylation step of beta-lactam hydrolysis.

Contribution of melanogenic proteins to the heterogeneous pigmentation of human melanocytes

Human melanocytes from individuals with different skin types, as well as from the skin of the same individual, are heterogeneous in their melanin content. This heterogeneity may be attributed to differences in the activity and expression of the three melanogenic proteins: tyrosinase and tyrosinase-related proteins 1 and 2 (gp75 and DOPAchrome tautomerase, respectively), which in turn are affected by certain regulatory factors. Established melanocyte strains that exhibited intrinsic melanogenic heterogeneity could be separated into subpopulations according to density and melanin content by Percoll density gradient centrifugation. The least melanotic subpopulation consisted of melanocytes that contained an active tyrosinase enzyme and a low amount of melanin. Tyrosinase activity and the quantities of tyrosinase enzyme, tyrosinase-related protein-1 and DOPAchrome tautomerase gradually increased with increased melanin content and Percoll density of the isolated melanocyte subpopulations. We have found a direct correlation between melanin content, tyrosinase activity and the expression of the three melanogenic proteins in melanocyte strains established from different skin types. Addition of the two epidermal cytokines, tumor necrosis factor-alpha or interleukin-1 alpha, to cultures of human melanocytes from different skin types caused decreased proliferation, tyrosinase activity and expression of tyrosinase, tyrosinase-related protein-1 and DOPAchrome tautomerase. Similar results were obtained when Percoll-derived melanocyte subpopulations were treated with tumor necrosis factor-alpha and interleukin-1 alpha. These results indicate that the variation in melanin content in human melanocytes is due to differences in the activity and expression of the melanogenic proteins, which are influenced by autocrine and paracrine factors.

Gap junction communication modulates [Ca2+]i oscillations and enzyme secretion in pancreatic acini

Global (all cells in an acinus) and focal (1-2 out of 10-15 cells) stimulation of pancreatic acini with bombesin or t-butyloxycarbonyl-Tyr(SO3)-Nle-Gly-Tyr-Asp-2-phenylethyl ester (CCKJ) together with modulation of gap junction (GJ) permeability by octanol and NO2- was used to study the role of GJ permeability in controlling [Ca2+]i oscillations and enzyme secretion. GJ permeability was quantitated by measuring fluorescence recovery after photobleaching. Octanol at 0.5 mM markedly reduced, whereas 15 mM NO2- increased GJ permeability. Focal application of bombesin caused synchronized oscillations in the entire acinus, whereas global stimulation resulted in asynchronous oscillations. Increasing GJ permeability with NO2- had no effect on bombesin-evoked [Ca2+]i oscillations. Octanol inhibited ongoing oscillations evoked by focal or global bombesin stimulation. However, when GJ were blocked prior to stimulation, subsequent global stimulation with bombesin induced long-lasting oscillations in all cells. Re-establishing GJ communication for as little as 37.5 s conferred GJ dependence on the order and time of [Ca2+]i spiking evoked by global bombesin stimulation. Focal and global stimulation with CCKJ gave different patterns of [Ca2+]i oscillations. However, in contrast to bombesin, inhibition of GJ with octanol had no effect on oscillations induced by global CCKJ stimulation. Increasing GJ permeability with NO2- synchronized CCKJ-stimulated oscillations by equalizing the amplitude and increasing the frequency in all cells within an acinus. These observations suggest that amplitude and frequency of [Ca2+]i oscillations can be regulated independently of each other, and that GJ permeable molecules modulate the frequency of [Ca2]i oscillation in an agonist-specific manner. Regardless of the agonist, increasing the frequency of oscillations by modulation of GJ permeability correlated with an increased enzyme secretion.