Acta pharmacol. et toxicol. 1983, 53, 245-249.

From the Department of Pharmacology, Odense University, J. B. Winslews Vej 19, DK-5000 Odense C, Denmark

Utilization of Adenosine Triphosphate in Rat Mast Cells during and after Secretion of Histamine in Response to Compound 48/80

BY Torben Johansen

(Received March 8, 1983; Accepted April 7, 1983)

Abstract: The adenosine triphosphate (ATP) content of rat mast cells and their lactate production were measured during and after secretion of histamine induced by compound 48/80. Antimycin A and oligomycin were used to block oxidative ATP synthesis, and 2-deoxyglucose (2-DG) was used t o block glycolytic ATP synthesis. Histamine secretion was completed after 10 sec. exposure of the cells to compound 48/80. During that time period there was an increased ATP-utilization of 0.15 pmol/103 cells. After completion of the secretory process there seemed to be an enhanced utilization of ATP of 0.40 pmol/103 cells/min., which may be associated with recovery of the cells.

Key-words: Histamine secretion - mast cells - ATP - compound 48/80 - rats.

Secretion of histamine by rat mast cells in response to compound 48/80 is an energy-requiring process- (Johansen & Chakravarty 1974; Peterson & Dia- mant 1974; Johansen & Chakravarty 1975), which utilizes cellular adenosine triphosphate (ATP) dur- ing the release of histamine (Johansen 1980a). After completion of the secretory process a per- sistent decrease of cellular ATP was found (Johan- sen & Chakravarty 1975; Johansen 1980a), and there was an increased cellular production of COZ and lactate from exogenous glucose (Svendstrup & Chakravarty 1977; Chakravarty & Serrensen 1974).

The present investigation was performed in order to determine the amount of ATP, which is utilized during and after secretion of histamine. This was completed 10 sec. after stimulation of the cells with compound 48/80, and the ATP-utiliza- tion for the secretory process was estimated to 0.15 pmol/103 cells. After secretion of histamine, the rate of ATP-utilization of the cells was enhanced by 0.40 pmol/103 cells per min.

Materials and Methods

Isolation of rat mast cells. Male Sprague-Dawley rats, 410-560 g, were used for the experiments. Mast cells were isolated by differential centrifugation in concentrated human serum albumin (Johansen & Chakravarty 1975). Finally the cells were suspended in Krebs-Ringer solution containing human serum albumin, 1 mg/ml, final pH 7.1-7.2. Mast cells: 96.3ik 1.2% (MeankS.E.M., N = 14) of cell population.

Incubation procedure. Mast cell suspensions from 1-3 rats were pooled and divided into aliquots with the same cell density in a final volume of 0.5 ml. These were used for the histamine release experiments and for determina- tion of the ATP content and the lactate production of the mast cells. In the last case cell density was 3.37X 10’ to 5.81 X 10’ cells/ml. In the other experiments the cell suspension contained 0.72X 10’ to 1.06X lo5 cells/ml. For the experiments in fig. 1 the cells were temperature equilibrated in a 37” bath for 10 min. and pretreated with 5 mM 2-deoxyglucose (2-DG) for 20 min. followed by 20 sec. preincubation with respiratory inhibitors (1 pM antimycin A and 1 pg/ml oligomycin). Then the cells were incubated with compound 48/80 (1 pg/ml) for 3 to 60sec. Samples for determination of spontaneous histamine release (i.e. compound 48/80 not present) in presence and

246 TORBEN JOHANSEN

absence of metabolic inhibitors and samples for deter- mination of histamine release and cellular ATP in the absence of inhibitors were included. For the experiments in fig. 2 and table 1 the cells were temperature equilibrated at 37" as above, pretreated with respiratory inhibitors (1 pM antimycin A and 1 pg/ml oligomycin) for 20min. and then incubated with compound 48/80 (1 pg/ml) for 10 to 30 min. Glucose, 5 mM, was used as substrate for the glycolysis in these experiments. Samples for determina- tion of the normal ATP content of untreated cells and samples for determination of lactate production in the absence of compound 48/80 but in presence of inhibitors and glucose were included. Control samples for deter- mination of histamine release in presence of respiratory inhibitors and glucose were also included.

Determination of histamine release, ATP content and lactate production of mast cells. The histamine release experiments were performed as described previously (Johansen & Chakravarty 1975). After incubation with compound 48/80, the reaction was stopped by adding seven times higher volume of ice-chilled Krebs-Ringer solution containing human serum albumin (1 mg/ml) to the cell suspensions. Histamine release was determined by the fluorometric method (Shore et al. 1959), omitting the extraction procedure. None of the reagents interfered with the determination of histamine.

For determination of ATP content and lactate produc-

6 0

W vl 0

W L

a,

E 0

2 40

E

c

g 2 0

s

0

I

0 20 40 60 Sec

Fig. la. Time course of histamine release induced by compound 48/80 from mast cells pretreated with glyco- lytic and respiratory inhibitors. Abscissa scale: time of incubation with compound 48/80. Ordinate scale: hista- mine release in percent of the total histamine content of the cells. Spontaneous histamine release in presence of metabolic inhibitors (mean 6.6%) deducted. In the ab- sence of inhibitors spontaneous histamine release was mean 4.4%. Mean value from three experiments; vertical

tion of the cells the incubation was stopped with chilled perchloric acid. After neutralization of the supernatant, the ATP content was determined by the bioluminescence technique using luciferin-luciferase from firefly lantern as described earlier (Johansen & Chakravarty 1975) and using internal standards for correction of inhibition by perchlorate. None of the reagents interfered with the measurement.

Lactate was measured according to the method de- scribed by Lowry & Passonneau (1972). Details of the method has been described previously (Johansen 1979). Internal standards and blanks without cells were used in the present experiments. Control experiments showed no lactate production by mast cells incubated in Krebs- Ringer solution in ice-chilled waterbath. The presence of cells had no effect on the recovery of added lactate as internal standard.

Materials. Human serum albumin was supplied by AB KABI (Stockholm, Sweden), antimycin A, oligomycin, 2- Deoxy-D-glucose, L-lactic acid, glutamic-pyruvic trans- aminase, 2-amino-2-methyl- I-propanol and glutamate monosodium by Sigma Chemical Company (St. Louis, U.S.A.), lactate dehydrogenase and NAD' by Boeh- ringer-Mannheim GmbH (Mannheim, W. Germany), and glucose by BDH Chemicals Ltd. (England). All other chemicals were of analytical grade.

The Krebs-Ringer solution contained (in mM) NaCl 139.8, KCI 4.7, MgSO4 1.2, CaC12 2.5, Na2HP04 2.5, KH2P04 0.6.

100 - - 2

8

8 50

c c

.I- 0

+ c W

c 0 U

+

a I- a

0 I I

0 20 40 60 Sec

Fig. Ib. Changes in the ATP content of mast cells during histamine secretion. The cells were preincubated with metabolic inhibitors and then incubated with ( 0 ) or without (0) compound 48/80. Abscissa scale: time of incubation of the cells with compound 48/80. Ordinate scale: ATP content in percent of control value from mast cells incubated in the absence of metabolic inhibitors and compound 48/80: 1.67*0.09 pmol/lO' cells (mean f S.E.M., N = 7). Mean value from four (45 and 60sec.), six (15 sec.) and seven experiments; vertical lines show

lines show S.E.M. S.E.M.

HISTAMINE SECRETION AND ATP-UTILIZATION 247

Table 1. Enhancement of lactate production by mast cells after histamine release induced by compound 48/80.

Lactate production, pmol/103 cells 50 min. 1 min. 20 min. 30 min. 1 min.

(observed) (calculated) preincubation incubation incubation

+ 0 + 0 §Histamine Expts. a b c (=20Xb) (a-c) (a-c)/30 release (%)

Compound 48/80 Compound 48/80 calculated values

1 2 3 4 5

Mean S.E.M.

86.1 78.3 1.72 1.57 31.4 54.7 1.82 32.5 103.9 86.7 2.08 1.73 34.6 69.3 2.31 55.7 96.7 84.5 1.93 1.69 33.8 62.9 2.10 51.4 98.2 84.6 1.96 1.69 33.8 64.4 2.15 33.9 92.4 83.9 1.85 1.68 33.6 58.8 1.96 35.9

95.5 83.6 1.91 1.67 33.4 62.0 2.07 41.9 3.0 1.4 0.06 0.03 0.5 2.5 0.08 4.8

*P<O.O1

5 Spontaneous histamine release 5.3%f0.07% (mean*S.E.M., n-5) deducted. * t-test for two groups of data.

Results

Changes in cellular ATP content during histamine release. Histamine release was completed after 10 sec. exposure of the cells to compound 48/80 (fig. la). A small inhibition of maximal histamine release was observed when compared with the release from control samples (mean 61.2%) incubated without metabolic inhibitors (P<0.025 by t-test for paired data). When secretion was completed, there was a significant decrease of cellular ATP of 9% (fig. lb) (P<0.005 by t-test for two groups of data). Pre- incubation of the cells with 2-DG decreased the ATP content to 76.3% (mean value) of control value from untreated cells. By adding respiratory inhibitors a further decrease to a value of 58.5% of control value was observed (P<O.OOl by t-test for two groups of data).

Cellular ATP content and lactate production after secretion of histamine.

After 10 to 30 min. incubation of the cells with compound 48/80, a stable steady state ATP level of 45% (mean value) of the normal value was ob- served. In the absence of compound 48/80, the steady state ATP level was 70% of the normal value (fig. 2). In parallel experiments cellular lactate production was studied by determination of the

100 1 d

0 L t C 0 U

u- 0

50 4- C aJ I

4- c 0 U

1 , a k a

0 I I

10 20 30 Min

Fig. 2. Changes in the ATP content of mast cells after incubation with compound 48/80 for 10 to 30 min. The cells were preincubated with respiratory inhibitors and glucose. Then the cells were incubated with ( 0 ) or without (0) compound 48/80. Abscissa scale: time after addition of compound 48/80. Ordinate scale: ATP content in percent of control value from mast cells incubated without metabolic inhibitors and glucose and without compound 48/80: 1.52f0.05 pmol/lO’ cells (meanf S.E.M. N=9). Histamine release was 44.9% (mean value), spontaneous release (mean 5.9%) deducted. Mean values from three experiments; vertical lines show S.E.M.

248 TORBEN JOHANSEN

lactate produced by the cells after 20 min. pre- incubation with respiratory inhibitors and glucose followed by 30 min. incubation with compound 48/80. As shown in table 1, compound 48/80 caused mean 41.9% histamine release and this was associated with a significant stimulation of the lactate production.

Discussion

The synthesis of energy-rich phosphate in ATP is associated with oxidative and glycolytic energy metabolism. Previously, a decrease in cellular ATP content was observed during histamine secretion induced by compound 48/80 (Johansen 1980a). Cellular energy production was inhibited but not completely blocked, since either glycolytic or respi- ratory inhibitors but not both were used in those experiments. As a consequence, the amount of ATP used for the secretory process could not be calculated from the observed changes in cellular ATP.

In the present study high concentrations of a combination of glycolytic and respiratory inhib- itors were used in order to decrease the rate of ATP- synthesis to a negligible value. 2-DG, 5 mM, completely blocked glycolysis in rat mast cells (Johansen 1980a). The concentration of antimycin A ( 1 pM) was five times the concentration, which completely blocked the I4C02-production from isolated mast cells incubated with ‘‘C-labelled pyruvate (Diamant et al. 1974). Oligomycin is known to inhibit the utilization of oxidative energy for the synthesis of ATP (Lardy et al. 1958). In relation to the protein content of the mast cells (Diamant & Lowry 1966) the oligomycin concen- tration used in the present experiments was over 20 times the value used by Huijing & Slater (1961) for an isolated mitochondria1 preparation.

In the absence of cellular ATP-synthesis the 9% decrease in mast cell ATP content during histamine release corresponded to an increased ATP-utiliza- tion of the secretory process of 0.15 pmol/103 cells. Previously, A23187-induced histamine secretion was found to require the same amount of energy (Johansen 1980b). It may be observed that the time course of histamine release was almost the same as that observed by Bloom & Chakravarty (1970), who used untreated mast cells.

When cellular energy production was inhibited but not blocked, the ATP-decrease observed dur- ing histamine release continued a few minutes after secretion was completed. Then a late, decreased steady state ATP level was found (Johansen 1980a). Similarly, in the absence of metabolic inhibitors, there was a late, decreased steady state ATP-level of mast cells exposed to compound 48/80, and this was not caused by lack of substrate (Johansen & Chakravarty 1975). In presence of respiratory inhibitors, cellular energy production occurs mainly through conversion of glucose to lactate. The rate of lactate production may corre- spond to the rate of cellular ATP-synthesis. Lactate accumulated during the whole period of both preincubation and incubation with compound 48/80. By correction for the amount of lactate produced during the preincubation period, the rate of lactate production in presence of compound 48/80 was calculated to 2.07 pmol/lO’ cells per min. In the absence of compound 48/80 the rate of lactate production was 1.67 pmol/lO’ cells per min. Thus, the enhanced production of energy of com- pound 48/80 treated cells corresponded to syn- thesis of 0.40 pmol ATP per lo3 cells per min. However, this did not contribute to normalization of the ATP content of these cells. The enhanced rate of energy production and the observation of a low ATP steady state level (fig. 2) seemed to indicate a requirement of the cells of a high amount of energy after completion of secretion, and this may by associated with recovery of the cell. Im- mediately after secretion coalescence of cavities and fusion processes of the plasma membrane have been demonstrated by Nielsen et al. (198 I), but no indication of increased synthesis of histamine and heparin was observed during the first few hours after secretion (Chakravarty 1983).

Conclusions.

Secretion of histamine from rat mast cells induced by compound 48/80 is an energy-requiring process. During secretion there was an increased utilization of 0.15 pmol ATP/103 cells. After completion of histamine release there seemed to be an enhanced ATP-utilization of 0.40 pmol/lO’ cells per min., which may be associated with recovery of the cells.

HISTAMINE SECRETION AND ATP-UTILIZATION 249

A c k n o w l e d g e m e n t s The technical assistance of Mrs. Annette Kragh

Rasmussen and Mrs. Susanne Nielsen is gratefully acknowledged. Thanks a re due t o Miss Yvonne Madsen for typewriting the manuscript. This work was supported by the Danish Medical Research Council, 512-15082, and funds obtained f rom Novos Foundation.

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