Role of cyclic GMP in submandibular gland secretion

Area of Science:

• Biochemistry
• Cell Signaling
• Physiology

Background:

• The role of cyclic nucleotides in glandular secretion is complex.
• Calcium ions (Ca2+) are critical second messengers in many cellular processes, including glandular function.
• Phosphodiesterase inhibitors can modulate intracellular cyclic nucleotide levels.

Purpose of the Study:

• To investigate the role of cyclic guanosine monophosphate (cGMP) in rat submandibular gland secretion.
• To determine the influence of cholinergic and adrenergic stimulation on cGMP levels.
• To elucidate the involvement of calcium and phosphodiesterase activity in cGMP regulation.

Main Methods:

• Incubation of rat submandibular gland slices.
• Measurement of cyclic GMP (cGMP) levels.
• Use of cholinergic and adrenergic agonists.
• Application of calcium (Ca2+) and a phosphodiesterase inhibitor.
• Utilisation of the divalent ionophore A23187.

Main Results:

• Cholinergic stimulation significantly increased cGMP levels in a Ca2+-dependent manner.
• The increase in cGMP required the presence of a phosphodiesterase inhibitor.
• Adrenergic agonists did not significantly elevate cGMP levels.
• Ca2+ addition to A23187-treated slices rapidly increased cGMP, independent of cholinergic stimulation.

Conclusions:

• cGMP may play a role in cholinergic-mediated potassium (K+) release from submandibular glands.
• cGMP is unlikely to be involved in alpha-adrenergic agonist-induced K+ release.
• cGMP does not appear to mediate protease secretion induced by alpha-adrenergic agonists.