Increased Fluid Secretion Research Articles

Effect of Cholera Toxin on Fluid Absorption and Villus Lymph Pressure in Dog Jejunal Mucosa

Dog jejunal mucosa exposed to purified cholera toxin secreted fluid in vivo. When it was studied in vitro, net fluid transport was from mucosal to serosal side or absorption. The fluid absorption rate was, however, markedly reduced. The villus lymph pressure was also decreased in the toxin-exposed villi. These findings indicate that the net fluid absorptive activity by the villus is reduced by the action of cholera toxin. Within a wide range of dose of cholera toxin or exposure time in vivo, the fluid absorption rate in vitro was diminished to the same extent (about 50% of the control value). On the other hand, the fluid secretion rate in vivo increased with increasing dose of toxin or exposure time. These findings suggest that cholera toxin reduces the absorptive function of the villus epithelium, but the excessive production of fluid involves other functional areas such as the crypts or microcirculatory disturbance, or both. The composition of the absorbate with respect to glucose, Na, and C1 was the same in the control and toxin-exposed mucosa, suggesting that a simultaneous toxin-induced secretion with a different composition might not occur in vitro. It is concluded that both a reduction of fluid absorption and an increase of fluid secretion from intestinal mucosa may be involved in net fluid production in cholera.

Hormones and excretion in locusts

Hormones present within the cerebral neurosecretory cell-corpus cardiacum complex exert both diuretic and antidiuretic effects upon the excretory system. The Malpighian tubules and rectum respond to the diuretic hormone, which increases fluid secretion by the tubules and reduces rectal reabsorption. The antidiuretic hormone increases rectal reabsorption but has little effect upon tubule function. Feeding is of prime importance in regulating the release of the diuretic hormone; the control of release of antidiuretic hormone is not yet understood. Locusts remain in water balance under a variety of environmental conditions by the regulation of their fecal water content. This regulation is exercised by the diuretic and antidiuretic hormones. The diuretic hormone may increase fluid secretion by Malpighian tubules by increasing the intracellular levels of cyclic 3′,5′-AMP. The nature and number of hormonal factors present in the cerebral endocrine system and the ventral nerve cord are discussed.

Intratesticular assay of follicle-stimulating hormone in hypophysectomized rats.

SummaryThe intratesticular injection of a single, 2 μg dose of NIH-FSH-S-2, was detectable histologically, in immature hypophysectomized rats, one day after the injection. FSH induced specific germ cell loss, Sertoli cell hypertrophy, and increased fluid secretion. Germ cell depletion was intensified after 3 days and following two, 2 μg FSH doses. After 5 days, during which time 2 μg FSH was given every other day, systemic absorption of the hormone was evidenced by germ cell loss in contralateral uninjected testes. Days 7 to 15 were histologically similar to day 5. The rapid early changes in germ cell population, and Sertoli cell stimulation following intratesticular injections of FSH in the immature hypophysectomized rat when contrasted with the control status of the uninjected contralateral testis, should provide a basis for a specific assay of this hormone.