Heart structure and beat in the stable fly, Stomoxys calcitrans

Abstract

The heart of the adult stable fly, Stomoxys calcitrans (L.), is suspended from the dorsal sclerites of the abdomen by strands of connective tissue, and supported from below by alary muscles that insert into a central band of longitudinal muscle just beneath the aorta. Valved openings occur in three of the heart segments. The central band of muscle beneath the heart is innervated but there is no well-defined lateral cardiac nervous system. The myocardium consists of a single layer of circular muscle composed of a series of muscle fibres that are joined dorsally and ventrally by intercalated discs in the midline of the insect. T-system tubules are closely associated with the sarcoplasmic reticulum, forming dyads. The heart rate of intact stable flies varied from short intervals of almost no activity to periods with a very rapid beat (126-294 pulses/min), and when the connections to the central nervous system were severed the heart beat became very regular (258 pulses/min). Slight pressure applied to the dorsal septum stopped myocardial contractions in that segment. The myocardium was insensitive to perfusion with M acetylcholine, L-aspartic acid, L-glutamic acid, A-aminobutyric acid, 5-hydroxytryptamine, octopamine, tyramine and proctolin lo-' M . However, Mn++ caused either anintermittent beat at lower concentrations (0.5 mM) or near arrest at higher concentrations (2 mM). 10

The hindgut muscularis of the stable fly, Stomoxys calcitrans: Some of its structural, motile and pharmacological properties

“…5A, B). These rapid pulsations showed a close similarity to the frequency of contractions of the larval heart of the stable fly [9], while the large spherical compressions of the ovary were implicated in the process of ovulation (Fig. 5E).…”

The hindgut muscularis of the stable fly, Stomoxys calcitrans: Some of its structural, motile and pharmacological properties

“…5A, B). These rapid pulsations showed a close similarity to the frequency of contractions of the larval heart of the stable fly [9], while the large spherical compressions of the ovary were implicated in the process of ovulation (Fig. 5E).…”

The ultrastructure of the Aedes aegypti heart

“…The heart consists of a single layer of cross-striated circular cardiomyocytes and this overall arrangement is maintained throughout the developmental stages investigated. Such circular cardiomyocyte organization appears to be conserved in insects, including Diptera (Jones, 1954;Cook and Meola, 1983;Angioy et al, 1999;Wasserthal, 1999;Glenn et al, 2010;Lehmacher et al, 2012), Lepidoptera (Sanger and McCann, 1968c), Blattaria (Edwards and Challice, 1960), Phasmatodea (Ejaz and Lange, 2008) and Heteroptera (Chiang et al, 1990).…”

“…Histology also showed that the heart of Ae. aegypti is divided into chambers or compartments that are separated by valves or incurrent ostia (Cook and Meola, 1983;Angioy et al, 1999). The ostia consist of heart openings where hemolymph inflow occurs (Angioy et al, 1999).…”

Proctolin, an insect neuropeptide

“…of 100 synthetic proctolin analogues, 45 showed myotropic activity in insects; 2. 40 of these analogues are proctolin agonists and five are antagonists, [h-MeTyr 2 ]-proctolin being the most potent antagonist so far discovered; 3. both cardioexcitatory and myostimulatory effects depend on the presence and the type of the para substituent at position 2 of the proctolin sequence [50], and on the presence of the peptide bond hydrogen atom of the peptide bonds between Tyr-2 and Arg-1 [85] and between Tyr 2 -Leu 3 [72]; 4. additional substitution at the meta position of the Tyr phenyl ring probably facilitates interaction with the receptor site; 5. the Arg 1 , Leu 3 and Pro 4 residues in proctolin molecule are essential for its myotropic activity; 6. the myotropic effect of selected analogues on the locust oviduct or foregut bioassay suggest that there are probably sub-types of proctolin receptors in insects; 7. highly potent antagonistic properties are shown by proctolin analogues with the CH 3or -CH 2 -groups at C-h of the Tyr 2 residue, or weakly antagonistic activity was observed in cyclo-proctolin (an analogue with a rigid conformation), H-Arg-Tyr-Leu-OH and H-Tyr(m-NH 2 )-Leu-Pro-Thr-OH; 8. in conformational studies, an ordered structure is observed for proctolin and some of its analogues; 9. some proctolin analogues containing two or all D-residues have an unexpected super-agonistic activity on the heart of insects; 10. besides biological activity in insects, proctolin and some of its analogues have significant biological effects in mammals, manifested by analgesic or potent antagonistic activity in relation to the opiate receptor in rats.…”

The hindgut muscularis of the stable fly, Stomoxys calcitrans: Some of its structural, motile and pharmacological properties

“…5A, B). These rapid pulsations showed a close similarity to the frequency of contractions of the larval heart of the stable fly [9], while the large spherical compressions of the ovary were implicated in the process of ovulation (Fig. 5E).…”

The ultrastructure of the Aedes aegypti heart

“…The heart consists of a single layer of cross-striated circular cardiomyocytes and this overall arrangement is maintained throughout the developmental stages investigated. Such circular cardiomyocyte organization appears to be conserved in insects, including Diptera (Jones, 1954;Cook and Meola, 1983;Angioy et al, 1999;Wasserthal, 1999;Glenn et al, 2010;Lehmacher et al, 2012), Lepidoptera (Sanger and McCann, 1968c), Blattaria (Edwards and Challice, 1960), Phasmatodea (Ejaz and Lange, 2008) and Heteroptera (Chiang et al, 1990).…”

“…Histology also showed that the heart of Ae. aegypti is divided into chambers or compartments that are separated by valves or incurrent ostia (Cook and Meola, 1983;Angioy et al, 1999). The ostia consist of heart openings where hemolymph inflow occurs (Angioy et al, 1999).…”

Proctolin, an insect neuropeptide

“…of 100 synthetic proctolin analogues, 45 showed myotropic activity in insects; 2. 40 of these analogues are proctolin agonists and five are antagonists, [h-MeTyr 2 ]-proctolin being the most potent antagonist so far discovered; 3. both cardioexcitatory and myostimulatory effects depend on the presence and the type of the para substituent at position 2 of the proctolin sequence [50], and on the presence of the peptide bond hydrogen atom of the peptide bonds between Tyr-2 and Arg-1 [85] and between Tyr 2 -Leu 3 [72]; 4. additional substitution at the meta position of the Tyr phenyl ring probably facilitates interaction with the receptor site; 5. the Arg 1 , Leu 3 and Pro 4 residues in proctolin molecule are essential for its myotropic activity; 6. the myotropic effect of selected analogues on the locust oviduct or foregut bioassay suggest that there are probably sub-types of proctolin receptors in insects; 7. highly potent antagonistic properties are shown by proctolin analogues with the CH 3or -CH 2 -groups at C-h of the Tyr 2 residue, or weakly antagonistic activity was observed in cyclo-proctolin (an analogue with a rigid conformation), H-Arg-Tyr-Leu-OH and H-Tyr(m-NH 2 )-Leu-Pro-Thr-OH; 8. in conformational studies, an ordered structure is observed for proctolin and some of its analogues; 9. some proctolin analogues containing two or all D-residues have an unexpected super-agonistic activity on the heart of insects; 10. besides biological activity in insects, proctolin and some of its analogues have significant biological effects in mammals, manifested by analgesic or potent antagonistic activity in relation to the opiate receptor in rats.…”

The hindgut muscularis of the stable fly, Stomoxys calcitrans: Some of its structural, motile and pharmacological properties

“…5A, B). These rapid pulsations showed a close similarity to the frequency of contractions of the larval heart of the stable fly [9], while the large spherical compressions of the ovary were implicated in the process of ovulation (Fig. 5E).…”

The ultrastructure of the Aedes aegypti heart

“…The heart consists of a single layer of cross-striated circular cardiomyocytes and this overall arrangement is maintained throughout the developmental stages investigated. Such circular cardiomyocyte organization appears to be conserved in insects, including Diptera (Jones, 1954;Cook and Meola, 1983;Angioy et al, 1999;Wasserthal, 1999;Glenn et al, 2010;Lehmacher et al, 2012), Lepidoptera (Sanger and McCann, 1968c), Blattaria (Edwards and Challice, 1960), Phasmatodea (Ejaz and Lange, 2008) and Heteroptera (Chiang et al, 1990).…”

“…Histology also showed that the heart of Ae. aegypti is divided into chambers or compartments that are separated by valves or incurrent ostia (Cook and Meola, 1983;Angioy et al, 1999). The ostia consist of heart openings where hemolymph inflow occurs (Angioy et al, 1999).…”

Proctolin, an insect neuropeptide

“…of 100 synthetic proctolin analogues, 45 showed myotropic activity in insects; 2. 40 of these analogues are proctolin agonists and five are antagonists, [h-MeTyr 2 ]-proctolin being the most potent antagonist so far discovered; 3. both cardioexcitatory and myostimulatory effects depend on the presence and the type of the para substituent at position 2 of the proctolin sequence [50], and on the presence of the peptide bond hydrogen atom of the peptide bonds between Tyr-2 and Arg-1 [85] and between Tyr 2 -Leu 3 [72]; 4. additional substitution at the meta position of the Tyr phenyl ring probably facilitates interaction with the receptor site; 5. the Arg 1 , Leu 3 and Pro 4 residues in proctolin molecule are essential for its myotropic activity; 6. the myotropic effect of selected analogues on the locust oviduct or foregut bioassay suggest that there are probably sub-types of proctolin receptors in insects; 7. highly potent antagonistic properties are shown by proctolin analogues with the CH 3or -CH 2 -groups at C-h of the Tyr 2 residue, or weakly antagonistic activity was observed in cyclo-proctolin (an analogue with a rigid conformation), H-Arg-Tyr-Leu-OH and H-Tyr(m-NH 2 )-Leu-Pro-Thr-OH; 8. in conformational studies, an ordered structure is observed for proctolin and some of its analogues; 9. some proctolin analogues containing two or all D-residues have an unexpected super-agonistic activity on the heart of insects; 10. besides biological activity in insects, proctolin and some of its analogues have significant biological effects in mammals, manifested by analgesic or potent antagonistic activity in relation to the opiate receptor in rats.…”