SHORT COMMUNICATION: EFFECTS OF NIFEDIPINE AND BAY-K-8644 ON THE RELEASE OF CATECHOLAMINES FROM THE DOG ADRENAL GLAND IN RESPONSE TO SPLANCHNIC NERVE STIMULATION

This study was to investigate if endogenous pituitary adenylate cyclase-activating polypeptide (PACAP) can be released during direct splanchnic nerve stimulation in vivo and to determine whether PACAP in the adrenal gland can modulate the medullary response to sympathoadrenal reflex. The output of adrenal catecholamine and PACAP-38-like immunoreactivity (PACAP-38-ir) increased in a frequency-dependent manner after direct splanchnic nerve stimulation (0.2–20 Hz). Both responses were highly reproducible, and PACAP-38-ir output closely correlated with catecholamine output. Sodium nitroprusside (SNP; 0.1 mg/kg iv bolus) caused a severe hypotension resulting in marked increases in catecholamine secretion. In the presence of local PACAP-27 (125 ng), the maximum catecholamine response to SNP was significantly potentiated in a synergistic manner compared with that obtained in the group receiving SNP or PACAP-27 alone. The study indicates that endogenous PACAP-38 can be released particularly when the sympathoadrenal system is highly activated and that the local exogenous PACAP-27 enhanced the reflex-induced catecholamine release, suggesting collectively a facilitating role of PACAP as neuromodulator in the sympathoadrenal function in vivo.

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Correlation between neural release of VIP and adrenomedullary catecholamine secretion in vivo

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.268.6.r1449 ◽

1995 ◽

Vol 268 (6) ◽

pp. R1449-R1455 ◽

Cited By ~ 2

Author(s):

R. Gaspo ◽

N. Yamaguchi ◽

J. de Champlain

Keyword(s):

Adrenal Gland ◽

Nerve Stimulation ◽

Splanchnic Nerve ◽

Dependent Manner ◽

Strongly Correlated ◽

Anesthetized Dogs ◽

Supramaximal Stimulation ◽

Dose Dependent ◽

Splanchnic Nerve Stimulation

The aim of the present study was to determine whether vasoactive intestinal peptide (VIP) can be released along with catecholamines from the adrenal gland in response to direct splanchnic nerve stimulation in anesthetized dogs. An attempt was made to verify whether VIP was released mainly from chromaffin cells or from the splanchnic nerve terminals. The first group received a supramaximal stimulation (12 V) given on the left splanchnic nerve at three successive frequencies of 0.2, 2, and 20 Hz. The second group received increasing doses of 1,1-dimethyl-4-phenylpiperazinium (DMPP) locally infused into the denervated left adrenal gland. In response to nerve stimulation, adrenal venous catecholamine concentration significantly increased in a frequency-dependent manner, whereas VIP-like immunoreactive substance (VIP-ir) reached a significant level only at the highest frequency. The multiple linear regression analyses revealed that the net increases in adrenal venous catecholamine concentrations were strongly correlated with combined variables of VIP-ir concentration and frequencies, indicating r = 0.915 and 0.949 (n = 42, P < 0.0001) for epinephrine and norepinephrine concentrations, respectively. In response to local DMPP infusion, adrenal venous catecholamines increased in a dose-dependent manner, whereas VIP-ir remained unchanged. The results indicate that VIP-ir is released along with catecholamines from the dog adrenal gland in response to direct splanchnic nerve stimulation in vivo. The study also suggests that VIP is mainly released from splanchnic nerve endings.

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Corelease of neuropeptide Y like immunoreactivity with catecholamines from the adrenal gland during splanchnic nerve stimulation in anesthetized dogs

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y90-050 ◽

1990 ◽

Vol 68 (3) ◽

pp. 363-369 ◽

Cited By ~ 8

Author(s):

Richard Briand ◽

Nobuharu Yamaguchi ◽

Jacques Gagne ◽

Tomohiko Kimura ◽

Lisa Farley ◽

...

Keyword(s):

Adrenal Gland ◽

Neuropeptide Y ◽

Nerve Stimulation ◽

Plasma Concentrations ◽

Splanchnic Nerve ◽

Maximum Output ◽

Burst Stimulation ◽

High Frequencies ◽

Anesthetized Dogs ◽

Splanchnic Nerve Stimulation

The release of neuropeptide Y like immunoreactivity (NPY-li) from the adrenal gland was studied in relation to the secretion of catecholamines (CA:NE, norepinephrine; E, epinephrine) during the left splanchnic nerve stimulation in thiopental–chloralose anesthetized dogs (n = 16). Plasma concentrations of NE, E, and NPY-li were determined in the left adrenal venous and aortic blood. Adrenal outputs of NPY-li, NE, and E were 2.4 ± 0.4, 1.4 ± 0.2, and 7.3 ± 1.7 ng/min, under basal conditions, respectively. These values increased significantly (p < 0.05; n = 8) in response to a continuous stepwise stimulation at frequencies of 1, 3, and 10 Hz given at 3-min intervals during 9 min, reaching a maximum output of 4.6 ± 0.9 (NPY-li), 240.2 ± 50.2 (NE), and 1412.5 ± 309.7 ng/min (E) at a frequency of 10 Hz. Burst electrical stimulation at 40 Hz for 1 s at 10-s intervals for a period of 10 min produced similar increases (p < 0.05) in the release of NPY-li (4.8 ± 1.0 ng/min, n = 8), NE (283.5 ± 144.3 ng/min, n = 8), and E (1133.5 ± 430.6 ng/min, n = 8). Adrenal NPY-li output was significantly correlated with adrenal NE output (r = 0.606; n = 24; p < 0.05) and adrenal E output (r = 0.640; n = 24; p < 0.05) in dogs receiving the burst stimulation. The present findings demonstrate that NPY-li is coreleased with NE and E from the adrenal gland in response to direct splanchnic nerve stepwise or burst stimulation at high frequencies in anesthetized dogs. It is thus possible that the adrenal medullary NPY-li contributes to the modulation of circulating NPY-li levels under various physiopathological conditions.Key words: adrenal medulla, burst stimulation, catecholamines, corelease, neuropeptide Y, splanchnic nerves.

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