Noradrenaline (NA) is a catecholamine with multiple roles including as a hormone and a neurotransmitter. Cellular secretory activities are enhanced by adrenergic stimuli as well as by cholinergic stimuli. The present study aimed to determine which adrenoceptors play a role in controlling intracellular calcium ion ([Ca 2+ ] i ) level in acinar cells of rat lacrimal glands. Expression of mRNA for adrenoceptor subtypes in the acinar cells was assessed using RT-PCR. ] i increase. The peroxidase activity was quantified as a measure of mucin secretion. Ca 2+ -dependent exocytotic secretion of peroxidase was detected in rat lacrimal glands. The RT-PCR results showed that MUC1, MUC4, MUC5AC, MUC5B, and MUC16 were expressed in acinar cells. These findings indicated that NA activates α1-adrenoceptors, which were found to be the main receptors in Ca 2+ -related cell homeostasis and protein (including mucin) secretion in lacrimal glands.The lacrimal gland is the main contributor to the aqueous component of the preocular tear film, which contains water, electrolytes, proteins, peroxidase, mucins, and lactoferrin. The lacrimal gland is composed of several cell types, including myoepithelial cells, ductal cells, goblet cells, and acinar cells, which are the major cell type constituting 80% of the gland. Acinar cells are highly polarized and joined by tight junctions at the luminal membrane, creating distinct basolateral and apical membranes (12). Goblet cells are a source of mucus in tears and secrete different types of mucins onto the ocular surface, especially in the conjunctiva. Although the number of goblet cells increases in the nasolacrimal duct, as the diameter of the nasolacrimal duct lumen is narrower than that of the lacrimal sac. Regulation of lacrimal gland fluid secretions is under neural control; activation of the sensory nerves in the cornea and conjunctiva initiates an afferent pathway leading to the central nervous system, which subsequently activates an efferent pathway that stimulates parasympathetic and sympathetic nerves, and ultimately, the lacrimal gland (32). The appropriate amount and composition of lacrimal gland fluid are crucial for a healthy, intact ocular surface (14). Sympathetic nerves release the catecholamine noradrenaline (NA). Catecholamines bind to adreno-

5-hydroxytriptamine (5-HT: serotonin) is an important transmitter that causes vessel constriction, although few studies have examined the effect of 5-HT on venous smooth muscles. The intracellular Ca 2+ concentration ([Ca 2+ ] i ) plays an essential role in stimulus-response coupling in numerous tissue/cells including vascular smooth muscle cells. The present study was performed to examine whether differences between arteries and veins in the response to 5-HT can be detected under confocal microscope with respect to [Ca 2+ ] i dynamics. In posterior ciliary arteries of rats, 5-HT induced a [Ca 2+ ] i increase. The 5-HT-induced responses were caused by both Ca 2+ influx and mobilization. Agonist and antagonist experiments revealed that arterial smooth muscles possess 5-HT 1a, 1b, 2 (Gprotein-coupled type) and 5-HT 3 (ion channel type) receptors, and that 5-HT 2 in particular plays a major role in these responses. For vorticose veins, the 5-HT-induced responses were also caused by both Ca 2+ influx and mobilization. However, the cAMP dependent pathway (5-HT 4-7 ) was found to be significant in vasocontraction with respect to 5-HT in these vessels. Thus, Ca 2+ mobilization was induced by 5-HT 2 and 5-HT 4-7 in a vessel-dependent manner, whereas Ca 2+ influx universally was induced by 5-HT 3 . These results indicate that the posterior ciliary arteries and vorticose veins in the same tissue might differ greatly in their responses to stimulus.Retinal vein occlusion is the second most common retinal vascular disorder after diabetic retinopathy and is considered to be an important cause of visual impairment (9, 54). Ischemic disorders of the optic nerve constitute an important cause of visual loss (7, 30). For example, ischemic optic neuropathy, an acute disorder of the optic nerve, is now known to be a common yet serious vision-threatening disease in middle-aged and elderly populations (13,72). Similarly, evidence is mounting that vascular insufficiency in the intraorbital portion of the optic nerve might play an important role in amorose glaucomatous optic neuropathy and papilloedema (65, 83). The main vascular sources of the intraorbital portion of the optic nerve consist of the branches of the posterior ciliary artery and the central retinal artery (29,36,50,79). The choroid blood vessels of the eye provide 80-95% of the blood to the ocular structures including the outer retina and ciliary processes (6). The central retinal artery supplies the optic nerve and the inner retina, while the posterior ciliary artery pierces the sclera to enter the choroidal coat of the eye. The central retinal artery ends without significant anastomoses (32). The choroidal vessels are innervated by sympathetic and parasympathetic nerves; the parasympathetic innervation of the choroid derives from the ipsilateral pterygopalatine ganglion (59). Parasympathetic nerve stimulation produces nitric oxide-mediated vasodilation, which