Further studies on protein secretion by rat submandibular glands in response to the beta 1- and alpha 1- adrenoceptor stimuli during postnatal development.

: Developmental changes in salivary proteins secreted by the submandibular glands of male rats from 2 to 10 weeks of age in response to the beta 1- and alpha 1-adrenoceptor agonists, isoproterenol, methoxamine, dopamine, phenylephrine, epinephrine, norepinephrine and alpha-methylnoradrenaline, were studied by different electrophoreses and amino acid analysis. The electrophoretic patterns of proteins secreted by the glands in response to both stimuli changed dramatically every week up to 7 weeks of age, but thereafter appeared similar to those of adult submandibular salivary proteins. At 2 and 3 weeks of age, a few differences were found between the types of proteins secreted in response to two stimuli. These findings were also confirmed by an analysis of amino acid composition. The glandular levels of cGMP from 2 weeks and cAMP from 3 weeks of age were significantly elevated in response to methoxamine and isoproterenol. We conclude that functional maturation precedes morphological maturation in the submandibular glands of male rats.