Taizo Masuhara

Sialogogic activities of SNI-2011 compared with those of pilocarpine and McN-A-343 in rat salivary glands: Identification of a potential therapeutic agent for treatment of Sjörgen's syndrome

1. We examined the sialogogic activities in rat major salivary glands of SNI-2011, in comparison with those of pilocarpine and McN-A-343, and we characterized the subtypes of muscarine receptors that are involved in the sialogogic responses to SNI-2011 and McN-A-343. 2. SNI-2011 at doses ranging from 1 to 10 mg/kg (i.v.) increased the secretion of saliva in a dose-dependent manner. The dose-response curves for SNI-2011 were approximately parallel to curves for pilocarpine but the potency of SNI-2011 was about 25-fold lower than that of pilocarpine. 3. The total volume of saliva secreted in response to McN-A-343 was very much less than that secreted in response to SNI-2011. 4. The salivation induced by SNI-2011 and by McN-A-343 was inhibited by various antagonists with the following rank order of potency: 4-DAMP >> pirenzepine >> AF-DX 116. 5. Our results suggest that the sialogogic effects of SNI-2011 and McN-A-343 are mediated by direct stimulation of M3 receptors in salivary glands and that SNI-2011 may prove useful in the management of xerostomia in patients with Sjögrens syndrome.

Comparative Pathogenicity of a Wild-Type Strain and Respiratory Mutants of Candida albicans in Mice

The pathogenicity of a parent wild-type strain and three respiratory mutants of Candida albicans was examined in intravenously infected mice. The wild-type strain K grew well in the kidney and caused severe candidosis, and the 21-day LD50 value was 7.2 x 10(6) cells/mouse. A mutant with a low rate of respiration (KRD-8) whose growth rate in vitro was somewhat lower than that of the wild type, produced germ tubes in vitro to the same extent as the wild-type strain and was associated with mortality rates similar to those of the wild-type strain. Two respiration-deficient (petite) mutants (KRD-19 and KRD-51), whose growth rates in vitro were far lower than that of the wild-type strain, could neither colonize the kidney nor cause fatal infection, even at a dose of 10(8) cells/mouse. Formation of germ tubes and hyphal growth in vitro of the petite mutants were less extensive than those of the wild-type strain or KRD-8. Extracellular proteinase was produced at pH 3.5 by the wild-type strain and by KRD-8 but not by the petite mutants. From these results, it is most likely that the nonlethality of infection by the petite mutants in mice results primarily from the low capacity of growth of these mutants, even though the inability of the petite mutants to produce extracellular proteinase may be also related to some extent to their avirulence.

Effects of vasoactive intestinal peptide and its homologues on the acetylcholine-mediated secretion of fluid and protein from the rat submandibular gland

1. Acetylcholine-mediated (ACh-mediated) secretion of fluid and protein from rat submandibular glands was enhanced by intravenous injection of vasoactive intestinal peptide (VIP) and of secretin but not of peptide histidine isoleucine (PHI) or gastric inhibitory peptide (GIP). 2. When VIP and ACh were administered together, the enhancement of fluid secretion was inhibited by pretreatment with atropine or 4-DAMP and the enhancement of protein secretion was inhibited by pretreatment with atropine or phentolamine. 3. The enhancement of the ACh-induced secretion of fluid by secretin was strongly inhibited by pretreatment with atropine, and it was weakly inhibited by pretreatment with phentolamine or haloperidol. 4. These results suggest that the synergistic effects of VIP, PHI, secretin and GIP on the ACh-mediated secretion of fluid and protein from the rat submandibular gland do not reflect the extent of the structural homology of each peptide to VIP.