Sodium azide

Additional toxicological data

Administrative data

Endpoint:

additional toxicological information

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well conducted study, meeting generally accepted scientific principles, acceptable for assessment.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Activation of guanylate cyclase from rat liver and other tissues by sodium azide

Author:

Kimura H, Mittal CK, Murad F.

Year:

1975

Bibliographic source:

PMID: 240848, J Biol Chem. 250(20):8016-22

Reference 2

Reference Type:

review article or handbook

Title:

Unnamed

Year:

1981

Materials and methods

Type of study / information:

Activation of soluble guanylate cyclase after in vitro incubation of rat liver homogenate with sodium azide.

Test guideline

Qualifier:

no guideline available

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium azide

EC Number:

247-852-1

EC Name:

Sodium azide

Cas Number:

26628-22-8

Molecular formula:

N3Na

IUPAC Name:

sodium azide

Results and discussion

Any other information on results incl. tables

When soluble guanylate cyclase of liver homogenates was assayed with 1 mM sodium azide the reaction rate increased rapidly after a lag phase of about 8 min.

The effect of sodium azide was dependent upon its concentration between 0.01 and 0.25 mM. Less than 0.01 mM sodium azide had no effect with 5 or 10 min of preincubation. The concentration of sodium azide that produced half-maximal activation decreased with preincubation and was 0.04 mM with 10 min of preincubation.

The apparent K_mfor GTP with native soluble guanylate cyclase from rat liver was 35.3 ± 0.9 µM. After activation with 1 mM sodium azide the apparent K_mfor GTP was 113 ± 16 µM. Thus, sodium azide increased both maximal velocity and the K_mfor GTP.

Sodium azide (1 mM) also increased the activity of particulate guanylate cyclase from liver severalfold. Soluble and particulate enzyme from kidney were increased 13.1- and 6.4-fold, respectively. The largest effects of sodium azide were observed with particulate enzyme from cerebral cortex and cerebellum where about 60- and 19-fold stimulation was observed. However, in some experiments with cerebral cortex the sodium azide effect was only 10- to 20-fold. Soluble enzyme from cerebral cortex and cerebellum was not activated, nor were preparations from lung, heart, spleen, and small intestinal smooth muscle and mucosa.

Applicant's summary and conclusion

Executive summary:

Recent reports suggest that guanosine 3’:5’-monophosphate may act as a regulator of some biological processes. Sodium azide at concentration of 1 mM increased the activity of soluble guanylate cyclase from rat liver. The increased accumulation of guanosine 3':5'-monophosphate in reaction mixtures with sodium azide was not due to altered levels of substrate, GTP, or altered hydrolysis of guanosine 3':5'-monophosphate by cyclic nucleotide phosphodiesterase. The activation of guanylate cyclase was dependent upon sodium azide concentration and temperature.

The concentration of sodium azide that resulted in half-maximal activation was 0.04 mM. Sodium azide increased the apparent K_m for GTP from 35 to 113 µM.

The particulate enzyme from cerebral cortex and cerebellum was also activated with sodium azide, whereas the soluble enzyme from these tissues was not. Little or no effect of sodium azide was observed with preparations from lung, heart, and several other tissues. The activation of guanylate cyclase by sodium azide is complex and may be the result of the nucleophilic agent acting on the enzyme directly or what may be more likely on some other factor in liver preparations.