Postnatal changes in calcium and amylase of rat salivary glands, including calcium changes with senescence

Postnatal changes occur in glandular Ca concentration of rat parotid and submandibular glands. At 4 days of age, Ca concentration was low in both glands (only one-third to one-half that of adults) and increased gradually with age. The pattern of change was generally similar for male and female rats, but in submandibular gland, adult levels of 9-10 m-equiv./kg were reached by weaning, whereas for parotid gland, a gradual increase in Ca concentration occurred with adult levels of 9-10 m-equiv./kg reached by 7 weeks of age. The pattern of change was the same whether Ca concentration was expressed per kg wet or dry weight albeit water content changed with age. The changes in Ca concentration of parotid paralleled the age-associated increases in amylase activity of parotid gland. Amylase activity of submandibular gland was much less than that of parotid and similarly low at all ages examined, and did not parallel the age-associated increases in Ca concentration. The regulatory role of the sympathetic innervation on glandular Ca concentration was examined by effecting surgical denervation of parotid and submandibular glands at 8 days of age, and then determining Ca concentration of the denervated glands at 32 days. A three-fold increase in Ca concentration, similar to that following acute sympathectomy in adults, occurred in submandibular gland but no change was seen in parotid. An unexpectedly high concentration of Ca was also found in submandibular (but not parotid) gland of old rats.

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.

Calcium concentration of saliva and salivary glands of rat after cyclocytidine

Cyclocytidine (CC), in addition to its antitumor properties, also causes copious flow of saliva. Calcium concentration of CC-evoked saliva from submaxillary (SM) and parotid (PA) glands of adult rats was initially 7 meq/liter and 15 meq/liter, respectively, and thus resembled that of sympathetically evoked secretion. From previous data, as well as present data, this is expected since CC apparently causes release of norepinephrine (NE) from adrenergic nerve endings. Present data also confirm that CC causes NE release since a single dose of reserpine (RES) (5 mg/kg), administered 24 hr prior to injection of CC in order to cause depletion of NE prevented the action of CC. Furthermore, the NE released by CC acts principally on beta-adrenergic receptors since propranolol administered prior to CC caused a marked reduction in flow and [Ca] of saliva, and prevented the usual CC-induced depletion of glandular calcium. An increase in [Ca] of SM but not PA gland was also caused by chronic (daily injections of 500 mg/kg body wt for 3 days) administration of CC. The same threefold increase was observed 2 days after injection of a single dose of CC also. The increase in glandular calcium was not prevented by propranolol, thus suggesting that this effect of CC on glandular [Ca] was probably not beta-mediated. The calcium increase may, however, be the result of depletion of NE. Thus, [Ca] of SM of CC-treated rats, that of RES-treated rats, and that of rats treated with RES + CC were very similar. If the mechanism of action of the two drugs were different (not NE depletion), the combined action of the two would have been additive.

Effects of varying frequency of parasympathetic nerve stimulation on flow rate and ion concentrations of rat submandibular saliva

Effects of adrenergic antagonists on chorda-evoked salivary secretion were studied. Flow rate, Ca and Na concentration of the chorda-evoked saliva were related to changes in frequency of stimulation of the chorda. Thus, as frequency of stimulation was increased, flow rate, Ca and Na concentrations increased. However, K concentration of nerve-evoked saliva was similar at all frequencies. Depletion of gland Ca concentration was also dependent on frequency of the stimulation; at the highest frequency, there was a greater depletion of gland Ca concentration than at lower frequencies. The data indicate that stimulation of the chorda tympani nerve elicits what can be called pure parasympathetic saliva, as neither phentolamine nor propranolol blocked chorda-evoked secretion.

Effect of alpha- and beta-adrenergic agonists on fluid and calcium secretion by rat salivary glands

The separate roles of alpha- and beta-adrenergic receptors in regulating fluid and calcium (Ca) secretion by rat salivary glands were examined using phenylephrine (PE), an adrenergic agonist that acts predominantly on alpha-receptors, isoproterenol (ISO), an adrenergic agonist that acts predominantly on beta-receptors, and PE and ISO in combination with beta-adrenergic antagonist propranolol (PROP) and alpha-adrenergic antagonist phentolamine (PHENTO), respectively. PE evoked a greater volume of saliva from submandibular (SM) gland than from parotid (PA) gland, whereas ISO evoked a similar volume of saliva from both glands during 60-min of drug stimulation. PE even at a low dose had beta-adrenergic effects on flow rate of salivary glands because pretreatment of rats with PROP (1 mg/kg) 20 min before PE (5 mg/kg, i.p.) stimulation resulted in a 4-fold reduction in total volume of PE-evoked PA saliva. Thus alpha-adrenergic receptors play a major role in fluid secretion by SM glands but play only a minor role in PA glands. ISO evoked SM and PA saliva with Ca concentration higher than that evoked by PE. ISO (25 mg/kg, i.p.) also had an effect on alpha-adrenergic receptors as well as beta-adrenergic receptors. Although PHENTO did not significantly alter flow rate and volume of ISO-evoked PA or SM saliva, Ca concentration of ISO-evoked saliva was greatly potentiated by PHENTO. Total Ca output of ISO-evoked saliva from either gland was not significantly altered by PHENTO. Thus, in both salivary glands, activation of beta-adrenergic receptors evoked saliva with a high concentration of Ca.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Salivary secretion induced by substance P

Secretion of fluid, ions, and amylase from parotid and submaxillary glands of rat, induced by intravenous injection of substance P (SP), was examined. The action of SP on salivary glands, like physalaemin, resembled that of cholinergic stimulation. While SP-evoked salivary flow from both glands was blocked by atropine, atropine did not modify composition of SP-evoked saliva. The present study suggests that salivary secretion and secretion of ions and amylase evoked by SP are mediated via SP-sensitive cholinergic receptors and specific SP receptors, respectively.

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)

Nerve-stimulated secretion of calcium by rat submandibular gland

The comparative effects of electrical stimulation of parasympathetic (chorda tympani nerve) and sympathetic innervation to the rat submandibular gland on calcium secretion were examined. The separate roles of alpha- and beta-adrenergic receptors in the regulation of calcium secretion during sympathetic nerve stimulation were also determined. The present study shows that the parasympathetic and sympathetic innervations to rat submandibular gland have very different effects on [Ca] of saliva; the regulatory influence of the sympathetic is more prominent than that of the parasympathetic innervation; [Ca] of submandibular saliva evoked by chorda stimulation was about 25 times less than that of saliva evoked by sympathetic stimulation. However, since total volume of chorda-evoked submandibular saliva was about 20 times greater than that of sympathetically evoked saliva, the total output of calcium following stimulation of either autonomic branch was similar. Glandular depletion of calcium for both kinds of nerve stimulation was also similar. Comparison with previous studies on the rat parotid gland shows that the role of the parasympathetic innervation in regulation of [Ca] of saliva and glandular depletion of calcium differed in the two glands while that of the sympathetic innervation was generally similar for both submandibular and parotid glands. Calcium secretion from rat submandibular gland was decreased during sympathetic nerve stimulation in the presence of propranolol, a beta-adrenergic blocker, while it was greatly increased when the sympathetic nerve was stimulated in the presence of phentolamine, an alpha-adrenergic blocker. Thus, it was concluded that with both glands beta-adrenoceptors play the major role in the regulation of calcium secretion.

Studies on the transmission of human hepatitis A virus to stump-tailed monkey

The newly-caught stump-tailed monkeys (Macaca speciosa) with negative antibody to hepatitis A were inoculated with human hepatitis A virus. The following findings were observed in the monkeys after inoculation: (i) the elevation of activities of the serum glutamic-pyruvic transaminase, lactate dehydrogenase and its isoenzyme (LDH5), (ii) the seroconversion of antibody to hepatitis A virus. (iii) the shedding of hepatitis A antigen in feces. These findings show that the stump-tailed monkey (Macaca speciosa) is susceptible to infection of human hepatitis A virus. The virus recovered from the feces of the infected monkey, named as Hang-zhou A-1A strain of hepatitis A virus, has experienced two generations of successful transmission in monkeys.

Susceptibility of monkeys to human hepatitis A virus

A stump-tailed monkey, newly caught and without antibody to hepatitis B virus (HAV), was successfully infected with human HAV. The following alterations were observed in the monkey's functions: (1) elevation in activities of serum glutamic pyruvic transaminase, lactate dehydrogenase, and its type 5 isoenzyme (electrophoretically the fastest moving); (2) development of antibody to HAV; and (3) shedding of HAV antigen in feces. The virus isolated from the monkey, designated the Hangzhou A-1A strain of HAV, was serially transmitted to two other stump-tailed monkeys. Thus, the stump-tailed monkey (Macaca speciosa) is susceptible to infection with human HAV.

Cyclic AMP formation and release by cultured bone cells stimulated with prostaglandin E2

PGE2 produced a marked and dose-related increase in cAMP content of cultured bone cells and in the release of cAMP into the incubation medium. The amount of cAMP released from the cells by PGE2 was proportional to the cellular concentration, and was dependent upon the time of incubation with PGE2. The cAMP levels released into the media increased slowly at a linear rate during a 60 min treatment with PGE2. This release was blocked by theophylline, probenecid, ouabain and dinitrophenol, suggesting that the release of cAMP was not a simple diffusive process and required energy. SC-19220 reduced the formation of cAMP more than the release, suggesting that the formation and the release may arise from separate events. Inability of D600 to inhibit PGE2-induced release of cAMP indicates that the release does not require calcium.

Effect of cocaine and desmethylimipramine on the uptake, retention and metabolism of 3H-5-hydroxytryptamine in rat brain slices

Uptake and metabolism of 3H-5-dydroxytryptamine (3H-5-HT) in slices of hypothalamus, brain stem caudate nucleus and parietal cortex were examined in vitro. The results indicate that 3H-5-HT taken up by neurons is firmly retained and that there are regional differences in the uptake and retention of 3H-5-HT. For example, the caudate had a significantly greater maximum rate of uptake and binding (Vmax) than the other brain areas tested, particularly the cortex. In contrast the caudate appeared to have the lowest apparent for 3H-5-HT uptake (Km). Uptake and retention of 3H-5-HT by four brain areas were markedly inhibited by cocaine and desmethylimipramine (DMI) in vitro. The inhibitory effect of both drugs was noncompetitive in nature, with exception of thct that cocaine and DMI failed to reduce the formation of 3H-5-hydroxy-indoleacetic acid despite ther potent blocking action of 3H-5-HT uptake suggests that a significant amount of 3H-5-HT is oxidatively deaminated at extraneouronal sites. This extraneuronal metabolism of 5-hydroxytryptamine may play an play an important role in regulating the action of this neurotransmitter.

Effects of prostaglandins and other drugs on the cyclic AMP content of cultured bone cells

Prostaglandins of the E-series (PGE1 and PGE2) may be involved in disease-related, localized loss of bone. E-prostaglandins increase the cyclic AMP content of many cells; and, to determine if their effects on bone are mediated by cyclic AMP, we examined the effects of E-prostaglandins and of other agents on the cyclic AMP content of cultured bone cells. PGE2 produced a rapid, marked and dose-related increase in the cyclic AMP content of confluent monolayers of bone cells isolated from newborn rat calvaria. At 2.8 X 10(-6) M, PGE1 and PGE2 had approximately the same effect, while the effect of PGF2alpha was much less pronounced. In the presence of theophylline, PGE2 had a more marked effect than parathyroid hormone (PTH) and the combination of PGE2 and PTH had a synergistic effect. The divalent, cationic, ionophore, A23187, produced an increase in cellular cyclic AMP and had an additive effect in combination with PGE2. Synthetic salmon calcitonin (CT), which inhibits the bone resorptive effect of PGE2, increased cellular cyclic AMP and had an additive effect in combination with PGE2. A prostaglandin antagonist, SC-19220, partially inhibited the resorptive effect of PGE2 and reduced its effect on cellular cyclic AMP. The calcium antagonist, D600, inhibited the bone resorptive effects of PGE2 but had no effect on increased cellular cyclic AMP produced by PGE2. The marked effect of PGE2 on bone cell cyclic AMP suggests that this action is involved in the mechanism of PGE2-related bone loss. The fact that agents with different effects on PGE2-induced increases in cellular cyclic AMP can inhibit its resorptive actions, suggests that PGE2-induced changes in cyclic AMP may be related less to its resorptive actions than to its inhibitory effect on bone formation.