Studying salivary gland biochemistry and morphology in experimental animals
can yield information regarding general hormonal and environmental responses,
specific reactions affecting the oral cavity, as well as comparative aspects
of exocrine gland function. Environmental stimuli such as the action of catecho-
lamines are known to result in altered cell morphology and in changes of cyclic
AMP-dependent protein kinase (cA-PK) activity and cellular localization. In
this experiment, the biochemical and morphological changes in salivary glands
of space-flown rats were examined. .
Tissues were fixed and processed for electron microscopy. Salivary glands
were trimmed, homogenized, and separated into a soluble and particulate fraction
by centrifugation. The fractions were assayed for protein kinase activity, and
photo- affinity labeled to determine the distribution of protein kinase. A photoaffinity
probe (32P-labeled azido analog of cAMP) was used to determine the compartment-
al distribution of the R subunits in salivary gland cells.
Several aspects of phosphorylative protein modification in rat salivary glands
are apparently influenced by space flight conditions. Endogenous protein phosphoryl-
ation was increased in the parotid and in the sublingual glands of flight animals,
while measurements of cA-PK activity using an exogenous substrate showed no
significant difference in the flight animals. An increase in photoaffinity labeling
of regulatory subunits in the parotid cell particulate fractions from flight
animals was noted when compared to controls. Changes in cA-PK holoenzyme association
and subcellular subunit distribution suggest alterations in reactions which
are mediated via cyclic AMP, observations which are consistent with the reported
decrease in circulating catecholamines during simulated weightlessness. Testing
human saliva or salivary glands after space flight may yield useful indices
of cellular reactions related to catecholamine metabolism and thus afford some
insight into possible stress-associated responses.
Mednieks, M.I. and A.R. Hand: Biochemical and Morphological Evaluation of
the Effects of Spaceflight on Rat Salivary Glands. Abstract S-215. Proceedings
of the Seventh Annual Meeting on the IUPS Commission on Gravitational Physiology,
Niagara Falls, N.Y., October 13-18, 1985
Mednieks, M.I. and A.R. Hand: Biochemical and Morphological Evaluation of the
Effects of Spaceflight on Rat Salivary Glands. Physiologist, supl., vol. 28,
no. 6, 1985, pp. S215-S216.
Mednieks, M.I. and A.R. Hand: Salivary Gland Ultrastructure and Cyclic AMP-Dependent
Reactions in Spacelab-3 Rats. American Journal of Physiology, vol. 252, 1987,
pp. R233-R239.
Mednieks, M.I. et al.: Biochemical and Morphological Evaluation of the Consequences
of Spaceflight Conditions on the Structure and Function of Salivary Glands.
Abstract 83.18. 36th Annual Fall Meeting of the American Physiological Society,
Buffalo, N.Y., October 13-18, 1985, Physiologist, vol. 28. no. 4, 1985, p. 378.
¥ = publication of related ground-based study