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.

Mitogenic activity of rat salivary glands after electrical stimulation of parasympathetic nerves.

Electrical stimulation of the parasympathetic innervation to parotid or submandibular gland for 30 or 60 min resulted in increased [3H]thymidine uptake of both glands when measurements were made 18 h later. With 30 min of stimulation, the mean increase in parotid was 30% compared with unstimulated mates, and after 60 min of stimulation, the increase was 76%. Stimulation for 30 min with the adrenergic antagonists propranolol and phenoxybenzamine present showed an increase in [3H]thymidine of 76%. Stimulation of the chorda tympani for 30 min resulted in a mean increase of 59% in thymidine uptake of the sympathectomized submandibular gland compared with the unstimulated sympathectomized mate. beta-1,4-Galactosyltransferase activity of both stimulated parotid and submandibular glands also showed an increase of 71%. On the basis of the composition of the saliva in the oral cavity, we confirmed the identity of the stimulated nerve to parotid gland as the parasympathetic (auriculotemporal). Na, K, and amylase concentrations resembled closely the composition of saliva obtained directly from the duct with electrical stimulation of the parasympathetic nerve. These data provide the first evidence that electrical stimulation of the parasympathetic nerve to parotid and submandibular glands causes a mitogenic response in each of these organs; the data also provide the first evidence that electrical stimulation of the parasympathetic nerve causes an increase in levels of the enzyme beta-1,4-galactosyltransferase, known to be implicated in hyperplastic responses.

Effects of autonomic antagonists and growth factors on activity-mediated hyperplasia of rat parotid.

Administration of the autonomic antagonists atropine (1 mg/kg body wt), propranolol (2 mg/kg body wt), and phenoxybenzamine (2 mg/kg body wt) before the dietary change from all liquid to solid chow prevented an increase in uptake of [3H]thymidine into DNA of rat parotid gland associated with this dietary change. Administration of either the cholinergic antagonist alone or the adrenergic antagonists alone produced partial inhibition. The effects of complete autonomic blockade were not reversed when nerve growth factor (NGF) or epidermal growth factor (EGF) was given immediately after administration of antagonists. The effects of complete autonomic blockade were similar to those seen with surgical removal of the autonomic nerves to the parotid. The increased levels of beta 1-4-galactosyltransferase seen with the dietary change were not evident in rats given both muscarinic and adrenergic antagonists before the change to solid food nor did NGF or EGF reverse these inhibitory effects. Histological observation showed that the surgically denervated gland was morphologically less homogenous than the gland of rats given the antagonists and had infiltrating connective tissue. Nonetheless, with the reduced acinar cell pool, the [3H]thymidine uptake of the denervated parotid and that of antagonist-injected animals was similar.

Effects of carbamylcholine and isoproterenol on electrolyte fluxes in perfused main duct of submandibular gland of reserpinized rat.

Administration of reserpine (RES) at a dosage of 0.5 mg/kg body wt, ip daily for 7 days was found to lower the dose of carbamylcholine and isoproterenol that alters sodium and potassium transport by cells of the main duct of rat submandibular gland. In the perfused main excretory duct of the submandibular gland of the RES rat, administration of carbamylcholine at a dosage of 1 microgram/kg body wt, inhibited net efflux of sodium (17%) and administration of isoproterenol at a dosage of 2 micrograms/kg body wt increased net efflux of sodium (20%); these drugs, at the same dosages, did not induce significant change in electrolyte flux of normal rat. At a dosage of 5 micrograms/kg body wt, carbamylcholine decreased net influx of potassium (15%) in the RES rat but was without effect on normal rat. Isoproterenol at the dosage of 5 micrograms/kg body wt significantly inhibited net influx of potassium in both the RES rat and normal rat. The data suggested that the duct cells developed supersensitivity to sympathomimetic and parasympathomimetic stimulation after chronic RES treatment.

Effects of PGE1 alone and on sympathetically mediated Na, K transport in the perfused main submandibular duct of rat.

PGE1 was administered in 5 micrograms/kg doses every 5 min over a period of 70 min and Na and K transport in the perfused main duct of rat submandibular gland was examined during a period without stimulation of the sympathetic nerve as well as during stimulation of the sympathetic nerve. A 25% decrease in the amount of Na absorbed and a 42% decrease in the amount of K secreted occurred when PGE1 alone was administered; the same change occurred when the sympathetic nerve was stimulated in the presence of PGE1. These data show, for the first time, an effect of PGE1 alone on electrolyte transport, and suggest that specific PGE1 receptors are activated.

Effects of saliva from chronically reserpinized rat on Na and K transport in perfused main excretory duct of submandibular gland of normal rat.

Reserpine (RES) (0.5 mg/kg body wt, ip) was administered to rats for 7 days. On Day 8 saliva was evoked from these animals by intraperitoneal injection of pilocarpine nitrate (10 mg/kg body wt) and saliva from submandibular and parotid glands was collected separately. These collected salivas were used to perfuse through the main ducts of the submandibular glands of normal rats. After a control period of perfusion of the main duct with bicarbonate saline solution, parotid saliva from RES rats was perfused through the duct followed by regular perfusion. There was inhibition of Na absorption (22%) and K secretion (23%). Moreover, when submandibular saliva from treated rat was perfused through the main duct prior to regular perfusion, there was a decrease in Na absorption (31%) and K secretion (28%). In contrast, perfusion of the main duct with either parotid or submandibular saliva from normal rats caused no significant changes in Na and K transport. The present experiments confirm previous studies that there is some Na-inhibitory factor(s) present in saliva of the chronically RES-treated rat.

Effects of alpha, beta 1, and beta 2 adrenergic antagonists on the Na and K concentrations of sympathetic-nerve stimulated rat saliva.

Selective alpha and beta 1 and beta 2 adrenergic antagonists were used with electrical stimulation of the sympathetic innervation to parotid and submandibular glands of rats in order to delineate the role of the beta 1 and beta 2 adrenoceptors in regulation of salivary flow rate, Na reabsorption and K secretion from these glands. In parotid gland, [Na] of sympathetically evoked saliva in the presence of phentolamine (3 mg/kg, i.p.) was not different from that of nerve-evoked saliva in the presence of phentolamine and butoxamine (3 mg/kg, i.p.), except for the last 20 min of stimulation when [Na] of nerve-elicited saliva was higher. [K] of saliva with sympathetically evoked stimulation was the same in the presence of phentolamine alone as it was or in the presence of phentolamine and butoxamine. Again, there was no difference in salivary flow rate induced by either kind of stimulation, except for the first 10 min of stimulation, during which salivary flow rate of nerve-evoked saliva in the presence of phentolamine was lower than under the other conditions indicated. On the other hand, with submandibular gland, [Na] and [K] of nerve-elicited saliva in the presence of phentolamine were generally higher than levels of sympathetically evoked saliva in the presence of phentolamine and butoxamine. However, salivary flow rate of nerve-evoked saliva in the presence of phentolamine was generally lower than that of sympathetically evoked saliva in the presence of phentolamine and butoxamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of sympathetic nerve stimulation in the presence of specific adrenergic antagonists on Na, K, and Cl transport in perfused rat submandibular duct.

The role of beta 1- and beta 2-adrenoceptors in the modification of Na, K, and Cl transport in submandibular main duct of rat perfused with bicarbonate saline solution was studied with direct sympathetic nerve stimulation (4 V, 5 ms, 20 Hz) in the presence of specific adrenergic antagonists. Nerve stimulation in the presence of phenoxybenzamine (3 mg/kg b. wt., i.p.) and butoxamine (3 mg/kg b. w.t., i.p.) enhanced Na (44%) and Cl (35%) absorption but inhibited K (24%) secretion. On the other hand, the nerve-evoked response in the presence of phenoxybenzamine and metoprolol (3 mg/kg b. wt., i.p.) decreased K (19%) secretion without any changes in Na and Cl absorption. Therefore, the data suggest that beta 1- and beta 2-adrenoceptors may be present in the duct cells and activation of these receptors can modify electrolyte transport. Furthermore, prior administration of phenoxybenzamine, butoxamine, and metoprolol suppressed the effects of sympathetic nerve stimulation on transductal fluxes of Na, K and Cl; this indicates that the dosages of antagonists used were sufficiently high to block a nerve-evoked response.

Effects of electrical stimulation of the sympathetic nerve on the levels of beta-adrenergic and cholinergic muscarinic receptors and cyclic nucleotides in rat salivary glands.

After 30 and 60 min of stimulation, there were decrease of 16 to 19 per cent in beta-adrenoceptors in rat submandibular and parotid glands; a 10-min stimulation caused no change. Pre-incubation of the reaction mixtures (stimulated glands) with atenolol, a beta 1-antagonist, prevented most dihydroalprenolol (DHP) binding, but with butoxamine, a beta 2-antagonist, DHP binding was nearly complete. Thus the beta-receptor was of the beta 1-subtype. Muscarinic receptors of parotid gland showed no change after 10 min stimulation; after 30 min there was an increase of 12 per cent, and after 60 min, of 28 per cent. With submandibular gland, there was also no change at 10 min but, at 30 min, there was a 25 per cent increase, and at 60 min, a decrease of 18 per cent. Cyclic-AMP levels of parotid gland were markedly elevated after 10 min of stimulation (9-fold increase above controls) but, at 30 and 60 min, there was only a 1.6-fold increase. In submandibular gland, cyclic-AMP increased 10-fold at 10 min; at 30 min it was 2.5 times control levels and at 60 min, 1.9 times. Cyclic-GMP levels of parotid gland increased 34-fold after 30 or 60 min of nerve stimulation, but only 1.6-fold at 10 min. With submandibular gland, there was a 22-fold increase at 10 min, but at 30 and 60 min this was 15- and 12-fold, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Modification of dobutamine- and terbutaline-induced calcium and fluid secretion from rat salivary glands by atenolol and butoxamine.

Saliva was elicited from rat salivary glands by terbutaline at i.p. doses of 1, 5, 10 and 25 mg/kg b.wt. but not by doses of 0.1 or 0.5 mg/kg b.wt. Dobutamine elicited no secretion at 1 or 2 mg/kg but did at 5, 10 and 25 mg/kg b.wt. At 5 mg/kg terbutaline evoked nearly maximal volumes but with dobutamine, volumes were small at this dosage. At dosages of 10 and 25 mg/kg volumes with the two agonists were similar for parotid, but with submandibular, the volumes evoked by dobutamine were nearly two times as high as those elicited by terbutaline. Mean [Ca] of parotid saliva was also similar at all dosages of dobutamine (approximately 12 mEq/liter) and generally similar at all dosages of terbutaline (11-15 mEq/liter). Mean [Ca] of dobutamine-elicited submandibular saliva was approximately 6, 7 and 8 mEq/liter at 5, 10 and 25 mg/kg b.wt, respectively. With parotid, [Ca] was approximately 10 mEq/liter at 1, 5 and 10 mg/kg b.wt. but increased to 16-18 mEq/liter at 25 mg/kg. The time course of calcium secretion is described for both agonists at each dosage. [Ca] of both glands was decreased 60 min after i.p. injection of 10 or 25 mg/kg doses of dobutamine or terbutaline but was not changed by 5 mg/kg doses. Administration of 10 mg/kg of atenolol, the selective beta 1 antagonist, 20 min prior to injection of a 10 mg/kg dose of either terbutaline (beta 2 agonist) or dobutamine (beta 1 agonist) blocked secretion from both glands, and prevented the usual agonist-induced reduction in glandular concentration of calcium. Butoxamine, on the other hand, did not modify effects of terbutaline on fluid secretion or depletion of glandular calcium; it did partially inhibit dobutamine-induced fluid and calcium secretion but not depletion of glandular calcium. The present data suggest that beta adrenoceptors of salivary glands are predominantly of the beta 1 subtype and that it is these that regulate calcium and fluid secretion. On the basis of the data with the antagonists, it is concluded that terbutaline activates beta 1 rather than beta 2 receptors since the beta 1 antagonist but not the beta 2 antagonist blocked secretory responses to terbutaline.

Effects of adrenergic agonists on electrolyte transport in perfused salivary duct of rat.

The Na and Cl absorption and K secretion that occur in the main duct of rat submandibular gland are affected by adrenergic actions. The specific effects of stimulation of alpha-, beta 1- and beta 2-adrenergic receptors on net transepithelial fluxes of Na, K and Cl were investigated in microperfused main excretory duct of rat submandibular gland. Administration of methoxamine (2.5 micrograms . kg-1 . min-1, i.v.) resulted in marked decreases in net efflux (or absorption) of Na (38%) from the duct into the interstitial fluid and net influx (or secretion) of K (20%) from interstitial fluid into the ductal lumen without any effect on net efflux or reabsorption of Cl. A higher dose of methoxamine (5 micrograms . kg-1 . min-1, i.v.) produced further inhibition of net fluxes of Na and K without affecting net flux of Cl. Dobutamine (50 micrograms . kg-1 . min-1, i.v.) enhanced net effluxes of Na (40%) and Cl (300%) from the lumen but did not alter net K influx into the lumen. When the dosage of dobutamine was increased to 200 micrograms . kg-1 . min-1, an inhibition of net influx of K (28%) into ductal fluid was observed in addition to enhanced net fluxes of Na and Cl from the lumen. Administration of terbutaline (15 and 30 micrograms . kg-1 . min-1, i.v.) decreased net influx of K (30-40%) and increased net efflux of Cl (280%) without affecting net efflux of Na.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of substance P on Na and K transport in perfused main submandibular duct of rat.

Substance P (2 and 4 micrograms/kg . min, iv) caused an inhibition of net efflux of Na and net influx of K in perfused main excretory duct of rat submandibular gland. These effects could not be blocked by atropine sulfate. The data suggest that substance P receptors are present in the duct cells and play a role in the regulation of transductal electrolyte transport.

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.

Effects of adriamycin on calcium concentration and morphology of mouse salivary glands.

A large single dose (15 mg/kg body wt, ip) of the antitumor agent adriamycin (ADR) caused a marked increase in calcium concentration of submaxillary gland of female mice, and a smaller increase in the parotid gland within 2 days of injection. A small dose (2.5 mg/kg body wt) had no effect. The histological appearance of the glands was also changed and included an increase in size of granules and acinar cells of the submaxillary glands and a decrease in size of acinar cells of the parotid. At the EM level, there was evidence of mitochondrial alteration in the parotid but not in the submaxillary glands. Rough endoplasmic reticulum (RER) was markedly disorganized in the parotid, and abnormal whorls of RER were evident. Submaxillary glands showed no change in RER. Water content of either gland was unchanged from that of controls. Heart ventricles, unexpectedly, showed no change in calcium concentration from that of control tissues, at 3 h, 1, 2 or 4 days after ADR administration. The [Ca] changes induced by ADR in the submaxillary glands are not mediated via beta-adrenoceptor activation since propranolol did not alter the ADR-induced changes. The marked difference in response of the glands (and heart) to ADR, suggests that the mechanisms involved in calcium homeostasis in these organs are very different.

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)

Influence of converting enzyme inhibition on renal hemodynamics and glomerular dynamics in sodium-restricted dogs.

Clearance and micropuncture experiments were performed to evaluate the influence of converting enzyme inhibition (CEI) (SQ 14,225) on renal hemodynamics, glomerular filtration rate (GFR), segmental vascular resistances, and superficial nephron function in anesthetized sodium restricted dogs. In one series (n = 8), renal blood flow (RBF) and GFR exhibited a high degree of autoregulatory efficiency when renal arterial pressure (RAP) was reduced from 126 +/- 5 to 86 +/- 1 mm Hg. With RAP maintained at the reduced level, CEI elicited increases in RBF (3.9 +/- 0.3 to 5.8 +/- 0.5 ml/min per g kw) and GFR (0.81 +/- 0.03 to 0.94 +/- 0.04 ml/min per g kw). With return of RAP to spontaneous levels during continued CEI, RBF and GFR autoregulatory efficiency was maintained, and was similar to that observed in control dogs subjected to the same procedures (n = 5). In the micropuncture experiments (n = 12), RAP was maintained at the reduced level (87.5 +/- .9 mm Hg), and measurements were made before and during CEI. Proximal tubule pressure, peritubular capillary pressure, stop flow pressure, and single nephron GFR (SNGFR) increased significantly. Regression analysis suggested that the increases in SNGFR were associated with small increases in the filtration coefficient. CEI reduced preglomerular resistance by 29% to 35% and efferent arteriolar resistance by 24% to 32%. These results indicate that the increased activity of the renin-angiotensin system that occurs during salt restriction exerts approximately equivalent vasoconstrictor influences on both preglomerular and postglomerular vascular resistance elements.

Effects on rat parotid amylase and Ca of alpha- and beta-adrenergic sympathetic stimulation.

The roles of alpha- and beta-adrenergic receptors in the regulation of the secretion of amylase and calcium from rat parotid gland were studied by using direct electrical stimulation of the sympathetic innervation to the gland in the presence of selective adrenergic blocking agents. When phenoxybenzamine was administered intraperitoneally 25 min prior to nerve stimulation, the highest [Ca] (12-14 meq/liter) and amylase activity (1,000 mg/microliter) in the evoked saliva were observed. On the other hand, stimulation of the nerve in the presence of propranolol evoked a saliva that contained the lowest [Ca] (5-6 meq/liter) and amylase activity (170 mg/microliter). Furthermore, salivary flow (4.27 +/- 0.42 microliter/min X g) induced by sympathetic nerve stimulation in the presence of phenoxybenzamine was higher than that induced by sympathetic nerve stimulation in the presence of propranolol (2.55 +/- 0.39 microliter/min X g). Therefore, it was concluded that beta-adrenergic receptors play the major role in the regulation of salivary flow and the secretion of amylase and calcium, whereas alpha-adrenergic receptors play a minor role in the regulation of these parameters.