Abstract
When injected arterially, serotonin (5-hydroxytryptamine; 5-HT) has been shown to elicit naturally sized urea pulse events in the gulf toadfish, Opsanus beta. The goal of the present study was to determine which 5-HT receptor(s) was involved in mediating this serotonergic stimulation of the pulsatile excretion mechanism. Toadfish were surgically implanted with caudal arterial catheters and intraperitoneal catheters and injected with either 8-OH-DPAT (1 μmol kg -1), a selective 5-HT1A receptor agonist, α-methyl-5-HT (1 μmol kg-1), a 5-HT2 receptor agonist, or ketanserin, a 5-HT2 receptor antagonist (0.01, 0.1, 1 and 10 μmol kg-1) plus α-methyl-5-HT. 8-OH-DPAT injection did not mediate an increase in urea excretion, ruling out the involvement of 5-HT1A receptors in pulsatile excretion. However, within 5 min, α-methyl-5-HT injection caused an increase in the excretion of urea in >95% (N=2T) of the fish injected, with an average pulse size of 652±102 μmol N kg-1 (N=26). With α-methyl-5-HT injection there was no corresponding increase in ammonia or [3H]PEG 4000 permeability. Urea pulses elicited by α-methyl-5-HT were inhibited in a dose-dependent fashion by the 5-HT2 receptor antagonist ketanserin, which at low doses caused a significant inhibition of pulse size and at higher doses significantly inhibited the occurrence of pulsatile excretion altogether. However, neither 8-OH-DPAT nor α-methyl 5-HT injection had an effect on plasma cortisol or plasma urea concentrations. These findings suggest the involvement of a 5-HT2-like receptor in the regulation of pulsatile urea excretion.
| Original language | English |
|---|---|
| Pages (from-to) | 2003-2010 |
| Number of pages | 8 |
| Journal | Journal of Experimental Biology |
| Volume | 207 |
| Issue number | 12 |
| DOIs | |
| State | Published - May 1 2004 |
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Keywords
- α-methyl-5-HT
- 8-OH-DPAT
- Ketanserin
- Serotonin
- Serotonin receptor
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Agricultural and Biological Sciences (miscellaneous)
Cite this
Dogmas and controversies in the handling of nitrogenous wastes : 5-HT 2-like receptors are involved in triggering pulsatile urea excretion in the gulf toadfish, Opsanus beta. / Mcdonald, Danielle M; Walsh, Patrick J.
In: Journal of Experimental Biology, Vol. 207, No. 12, 01.05.2004, p. 2003-2010.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Dogmas and controversies in the handling of nitrogenous wastes
T2 - 5-HT 2-like receptors are involved in triggering pulsatile urea excretion in the gulf toadfish, Opsanus beta
AU - Mcdonald, Danielle M
AU - Walsh, Patrick J.
PY - 2004/5/1
Y1 - 2004/5/1
N2 - When injected arterially, serotonin (5-hydroxytryptamine; 5-HT) has been shown to elicit naturally sized urea pulse events in the gulf toadfish, Opsanus beta. The goal of the present study was to determine which 5-HT receptor(s) was involved in mediating this serotonergic stimulation of the pulsatile excretion mechanism. Toadfish were surgically implanted with caudal arterial catheters and intraperitoneal catheters and injected with either 8-OH-DPAT (1 μmol kg -1), a selective 5-HT1A receptor agonist, α-methyl-5-HT (1 μmol kg-1), a 5-HT2 receptor agonist, or ketanserin, a 5-HT2 receptor antagonist (0.01, 0.1, 1 and 10 μmol kg-1) plus α-methyl-5-HT. 8-OH-DPAT injection did not mediate an increase in urea excretion, ruling out the involvement of 5-HT1A receptors in pulsatile excretion. However, within 5 min, α-methyl-5-HT injection caused an increase in the excretion of urea in >95% (N=2T) of the fish injected, with an average pulse size of 652±102 μmol N kg-1 (N=26). With α-methyl-5-HT injection there was no corresponding increase in ammonia or [3H]PEG 4000 permeability. Urea pulses elicited by α-methyl-5-HT were inhibited in a dose-dependent fashion by the 5-HT2 receptor antagonist ketanserin, which at low doses caused a significant inhibition of pulse size and at higher doses significantly inhibited the occurrence of pulsatile excretion altogether. However, neither 8-OH-DPAT nor α-methyl 5-HT injection had an effect on plasma cortisol or plasma urea concentrations. These findings suggest the involvement of a 5-HT2-like receptor in the regulation of pulsatile urea excretion.
AB - When injected arterially, serotonin (5-hydroxytryptamine; 5-HT) has been shown to elicit naturally sized urea pulse events in the gulf toadfish, Opsanus beta. The goal of the present study was to determine which 5-HT receptor(s) was involved in mediating this serotonergic stimulation of the pulsatile excretion mechanism. Toadfish were surgically implanted with caudal arterial catheters and intraperitoneal catheters and injected with either 8-OH-DPAT (1 μmol kg -1), a selective 5-HT1A receptor agonist, α-methyl-5-HT (1 μmol kg-1), a 5-HT2 receptor agonist, or ketanserin, a 5-HT2 receptor antagonist (0.01, 0.1, 1 and 10 μmol kg-1) plus α-methyl-5-HT. 8-OH-DPAT injection did not mediate an increase in urea excretion, ruling out the involvement of 5-HT1A receptors in pulsatile excretion. However, within 5 min, α-methyl-5-HT injection caused an increase in the excretion of urea in >95% (N=2T) of the fish injected, with an average pulse size of 652±102 μmol N kg-1 (N=26). With α-methyl-5-HT injection there was no corresponding increase in ammonia or [3H]PEG 4000 permeability. Urea pulses elicited by α-methyl-5-HT were inhibited in a dose-dependent fashion by the 5-HT2 receptor antagonist ketanserin, which at low doses caused a significant inhibition of pulse size and at higher doses significantly inhibited the occurrence of pulsatile excretion altogether. However, neither 8-OH-DPAT nor α-methyl 5-HT injection had an effect on plasma cortisol or plasma urea concentrations. These findings suggest the involvement of a 5-HT2-like receptor in the regulation of pulsatile urea excretion.
KW - α-methyl-5-HT
KW - 8-OH-DPAT
KW - Ketanserin
KW - Serotonin
KW - Serotonin receptor
UR - http://www.scopus.com/inward/record.url?scp=3042662811&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=3042662811&partnerID=8YFLogxK
U2 - 10.1242/jeb.00957
DO - 10.1242/jeb.00957
M3 - Article
C2 - 15143134
AN - SCOPUS:3042662811
VL - 207
SP - 2003
EP - 2010
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
SN - 0022-0949
IS - 12
ER -