Diuretic effects of selected Thai indigenous medicinal plants in rats.

Extracts of five indigenous Thai medicinal having ethnomedical application in the treatment of dysuria were investigated for their diuretic activity. Root extracts of Ananas comosus and Carica papaya, given orally to rats at a dose of 10 mg/kg, demonstrated significantly increased urine output (P < 0.01) which was 79 and 74%, respectively, of the effect of an equivalent dose of hydrochlorothiazide. Both plant extracts gave similar profiles of urinary electrolyte excretion to that of the hydrochlorothiazide. The analyses of the urinary osmolality and electrolyte excretion per unit time suggest the observed effect of A. comosus was intrinsic, whereas that of C. papaya may have resulted from a high salt content of this extract. However, our experimental evidence on the diuretic activities of the other three plants did not parallel their local utilization for dysuria. It was found that the rhizome of Imperata cylindrica apparently inhibited the urination of rats whereas the rhizome of Cyperus rotundus and the stem of Averrhoa carambola failed to demonstrate any diuretic activities. These results indicate that two of the plants investigated exert their action by causing diuresis. The other three plants need further investigation to determine their effectiveness in the treatment of dysuria.

Secretory responses to autonomic stimulation of rat salivary glands following reserpine treatment.

The response to stimulation of the parasympathetic innervation to parotid or submandibular glands of reserpinized rats was altered from that of untreated rats. Thus, acute reserpinization, like other types of sympathectomy, resulted in increase in volume of parasympathetically-evoked parotid or submandibular saliva when comparison was made with evoked saliva from untreated glands. As norepinephrine is depleted by reserpine, there was no response to stimulation of sympathetic nerves to these reserpinized glands. Adrenergic receptors were normally activated by administration of autonomic agonists. Thus a single high dose of reserpine can cause the same effects as those induced by chronic administration of low doses of reserpine, i.e. a 3-fold increase in calcium (Ca) concentration of submandibular gland but no change in Ca concentration of parotid gland. Although sympathetic stimulation caused no change in Ca concentration of submandibular or parotid glands of reserpine (acute)-treated rats, stimulation with isoproterenol (25 mg/kg, i.p., 60 min) produced a 32-35 per cent decrease in glandular Ca concentration from that of unstimulated reserpinized glands. Glands of untreated rats showed a 52 per cent depletion after 60 min of isoproterenol stimulation; however, Ca output in parotid saliva from reserpinized rat for 60 min of stimulation was not changed from that of untreated rats, but that of submandibular saliva was two times greater. Ca concentration of submandibular saliva was unchanged during 60 min-stimulation of reserpine-treated rats, but that of untreated rats decreased.

Calcium concentration of salivary glands and saliva after chemical or surgical sympathectomy.

Calcium concentration of the submaxillary (SM) gland of adult rat was increased to 2-3 times control levels 24 h after a single high dose of reserpine (RES) (5 mg/kg body weight), 6-hydroxydopamine (6-OHDA) (20 mg/kg body weight), or surgical removal of a superior cervical ganglion (Sx). The increase could also be induced within 24 h after a single injection of lower doses of RES (0.05, 0.5 mg/kg body weight). Increase in calcium concentration in the parotid (PA) was not found under any of the above conditions, but did occur transiently at times within 24 h. The increase in glandular calcium concentration was found to be temporally related to depletion of norepinephrine (NE). The time frame for initiation of calcium changes was not the same for chemical and surgical sympathectomy (Sx). Increase in calcium concentration occurred after onset of sympathectomy-induced degeneration secretion; the onset varied with the kind of sympathectomy, and was seen 1 h after drug administration with either RES or 6-OHDA, but not until about 13 h after surgical Sx. Similarly, NE was markedly depleted, but later with surgical than with chemical Sx. Furthermore, with both kinds of sympathectomy, depletion of NE occurred earlier with PA than with SM, since normal basal levels of NE of SM are 3 times as great (3400 ng/g wet weight), compared with PA levels (1300 ng/g wet weight). The fact that NED was the neurotransmitter eliciting the degeneration secretion was confirmed physiologically by examination of the composition of this secretion.(ABSTRACT TRUNCATED AT 250 WORDS)