Influence of oligopeptide aldehydes on intracellular Ca2+ concentration in rat pituitary cells
| Autor: | Iván Nagy, Gyula Horvath, Gábor B. Makara, G. Rappay, Angéla Gyévai |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Fura-2
Molecular Sequence Data chemistry.chemical_element Tripeptide Biology Calcium chemistry.chemical_compound Pituitary Gland Anterior Calcium flux Extracellular Animals Amino Acid Sequence Thyrotropin-Releasing Hormone Pharmacology Dose-Response Relationship Drug Voltage-dependent calcium channel Calcium channel Rats Inbred Strains 3-Pyridinecarboxylic acid 1 4-dihydro-2 6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)- Methyl ester Calcium Channel Blockers Rats EGTA chemistry Biochemistry Potassium Biophysics Female Oligopeptides |
| Zdroj: | European Journal of Pharmacology: Molecular Pharmacology. 225:305-312 |
| ISSN: | 0922-4106 |
| DOI: | 10.1016/0922-4106(92)90104-4 |
| Popis: | We investigated the effects of some synthetic tripeptide aldehydes, earlier shown to influence pituitary hormone secretion and 45Ca2+ uptake, on the intracellular free Ca2+ concentration ([Ca2+]i) of rat anterior pituitary cells in suspension. Boc-D-Phen- Leu-Phenylalaninal or Boc-D-Phe-Leu-Prolinal in the tested range of 1–100 or 200 μM, respectively, were ineffective in influencing basal [Ca2+]i but caused a concentration-dependent inhibition in K+ (25 mM)-induced [Ca2+]i elevation. The IC50 of both effects was about 50 μM. In contrast, they did not interfere with the stimulation caused by the calcium channel agonist BAY K 8644 and were also ineffective in influencing the receptor-mediated stimulus of thyrotropin-releasing hormone on [Ca2+]i. On the basis of the present and foregoing results the possible involvement of calcium channels is discussed, but different mechanisms mediating the tripeptide aldehyde inhibition are also considered. A third tripeptide aldehyde. Boc-Gln-Leu-Lysinal (Boc-GLL), showed ionophore-like properties. This nontoxic substance caused a dose-dependent rise up to 400% (at 100 μM) in [Ca2+]i. Its effect is not mediated by voltage-dependent calcium channels, as it cannot be inhibited either by the classicalp calcium channel antagonists verapamil and nifedipine, or by the above-mentioned inhibitory tripeptide aldehydes. When we decreased the extracellular Ca2+ concentration by the addition of 4 mM EGTA, the effect was inverted and Boc-GLL caused a large fall in [Ca2+]i. We suggest that Boc-GLL may open cell membrane pores through which Ca2+ moves along the concentration gradient. The calcium flux can be inhibited by 20 mM Mg2+ and 100 μM Co2+ but not by 500 μM La3+. Thus, tripeptide aldehydes. depending on their structure, may decrease or increase [Ca2+]i via uncoventional mechanisms and may serve as tools for dissecting details of cell calcium homeostasis. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|