Abstract
The transient receptor potential (TrpA—ankyrin) receptor has been linked to pathological conditions in cardiac function in mammals. To better understand the function of the TrpA1 in regulation of the heart, a Drosophila melanogaster model was used to express TrpA1 in heart and body wall muscles. Heartbeat of in intact larvae as well as hearts in situ, devoid of hormonal and neural input, indicate that strong over-expression of TrpA1 in larvae at 30 or 37 °C stopped the heart from beating, but in a diastolic state. Cardiac function recovered upon cooling after short exposure to high temperature. Parental control larvae (UAS-TrpA1) increased heart rate transiently at 30 and 37 °C but slowed at 37 °C within 3 min for in-situ preparations, while in-vivo larvae maintained a constant heart rate. The in-situ preparations maintained an elevated rate at 30 °C. The heartbeat in the TrpA1-expressing strains could not be revived at 37 °C with serotonin. Thus, TrpA1 activation may have allowed enough Ca2+ influx to activate K(Ca) channels into a form of diastolic stasis. TrpA1 activation in body wall muscle confirmed a depolarization of membrane. In contrast, blowfly Phaenicia sericata larvae increased heartbeat at 30 and 37 °C, demonstrating greater cardiac thermotolerance.
Document Type
Article
Publication Date
1-6-2021
Digital Object Identifier (DOI)
https://doi.org/10.3390/insects12010038
Funding Information
Chellgren Endowed Professor fund from the University of Kentucky to R.L.C. for supplies.
Related Content
The following are available online at https://www.mdpi.com/2075-445 0/12/1/38/s1, Figure S1: The heart rate for intact larvae. The heart rate increased in UAS-TrpA1- RNAi#1 and in 24B>TrpA1-RNAi#1 from 21 to at 37 ◦C (p < 0.05, Paired t-test). There is no significant difference from the background to the RNAi strain. Figure S2: The heart rate for the dissected background strain and TrpA1-RNAi expressed in all mesoderm. The heart rates increased in UASTrpA1-RNAi#1 from 21 to at 30 ◦C (p < 0.05, Paired t-test). The same strain showed variation upon exposure at 37 ◦C, with some larvae increasing in rate and others decreasing. After 2.5 min, the rates also continued to show variation with some preparations increased rates while other decreased. There is no significant difference from the background to the RNAi larvae. These animals were all raised at 21 ◦C. Figure S3: The heart rate for the dissected background and expression of TrpA1-RNAi in mesoderm for larvae raised at 21 ◦C and 27 ◦C for exposure to 30 ◦C. The heart rate increased in UAS-TrpA1-RNAi#1 and 24B>TrpA1-RNAi#1 from 21 ◦C to at 30 ◦C for larvae raised at 21 ◦C and 27 ◦C (p < 0.05, Paired t-test). The UAS-TrpA1-RNAi#2, 24>TrpA1-RNAi#2, UAS-GFP and 24B>GFP strain showed a lot of variation upon exposure 30 ◦C for being raised at 21 ◦C or 27 ◦C. There is no significant difference from background strains compared to the ones crossed to the 24B strain. Figure S4: The heart rate for the dissected background and expression of TrpA1-RNAi in mesoderm for larvae raised at 21 ◦C and 27 ◦C for exposure to 37 ◦C. The heart rate showed a lot of variation upon the initial exposure to 37 ◦C for most of the strains; however, after two and half minutes the rates generally decreased for all the strains. The UAS-TrpA1-RNAi#2, 24>TrpA1-RNAi#2, UAS-GFP and 24B>GFP strains showed a lot of variation upon exposure 37 ◦C for being raised at 21 ◦C or 27 ◦C. There is no significant difference from background strains compared to the ones crossed to the 24B strain. Figure S5: The heart rate for the dissected strains expressing TRPA-RNAi in heart specific tissue. The heart rate increased in Hand4.2>TrpA1-RNA#1 (A1, A2) and Tinc>TrpA1-RNAi#1 (B1, B2) from 21 ◦C to at 30 ◦C (p < 0.05, Paired t-test) for both conditions of larvae raised at 21 ◦C (A1,B1) as well as at 27 ◦C (A2,B2). The stains Hand4.2>TrpA1-RNAi#1 (A3, A4) and Tinc>TrpA1-RNAi#1 (B3, B4) upon initial exposure at 37 ◦C showed quite a bit of variation. However, at 37 ◦C after 2 and half minutes all rapidly decreased heart rate. The same trends were present for the larvae raised at 21 ◦C (A3,B3) as well as at 27 ◦C (A4,B4). There is no significant difference from background strains compared to the ones crossed to the heart specific strains. Figure S6: Controls for the expression of the RNAi strains crossed with the W118 strain for dissected preparations. The UAS-TrpA1-RNA#1/+ showed similar trends as UAS-TrpA1 in an increase in heart rate at 30 ◦C. The 24B>TrpA1-RNAi#1 as well as the backgrounds and controls (UAS-TrpA1-RNAi#1, UAS-TrpA1-RNAi#2, UAS-GFP, and 24B>GFP) all showed variation upon initial exposure to 37 ◦C and showed a decrease after two and half minutes at 37 ◦C. No significant difference occurred among the strains.
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Repository Citation
Marguerite, Nicole T.; Bernard, Jate; Harrison, Douglas A.; Harris, David; and Cooper, Robin L., "Effect of Temperature on Heart Rate for Phaenicia sericata and Drosophila melanogaster with Altered Expression of the TrpA1 Receptors" (2021). Biology Faculty Publications. 203.
https://uknowledge.uky.edu/biology_facpub/203
Supplementary file
Notes/Citation Information
Published in Insects, v. 12, issue 1, 38.
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).