Expression of two-pore domain potassium channels in nonhuman primate sperm

Abstract

Objective: Two-pore domain potassium channels (K(2P)) play integral roles in cell signaling pathways by modifying cell membrane resting potential. Here we describe the expression and function of K(2P) channels in nonhuman primate sperm.

Design: Experimental animal study, randomized blinded concentration-response experiments.

Setting: University-affiliated primate research center.

Animal(s): Male nonhuman primates.

Intervention(s): Western blot and immunofluorescent analysis of epididymal sperm samples. Kinematic measures (curvilinear velocity and lateral head displacement) and acrosome status were studied in epididymal sperm samples exposed to K(2P) agonist (docosahexaenoic acid) and antagonist (gadolinium).

Main outcome measure(s): Semiquantitative protein expression and cellular localization and quantitative changes in specific kinematic parameters and acrosome integrity.

Result(s): Molecular analysis demonstrated expression and specific regional distribution of TRAAK, TREK-1, and TASK-2 in nonhuman primate sperm. Docosahexaenoic acid produced a concentration-dependent increase in curvilinear velocity (P<.0001) with concomitant concentration-dependent reductions in lateral head displacement (P=.005). Gadolinium reduced velocity measures (P<.01) without significantly affecting lateral head displacement.

Conclusion(s): The results demonstrated expression and function of K(2P) potassium channels in nonhuman primate sperm for the first time. The unique, discrete distributions of K(2P) channels in nonhuman primate sperm suggest specific roles for this subfamily of ion channels in primate sperm function.

Figure 1

Demonstrates the expression of (A) TRAAK, (B) TREK-1 and (C) TASK-2 in non-human primate sperm (Macaca nemestrina). Columns 1, Rat brain extract; 2, native sperm. The asterisk (*) indicates protein bands at ~100 KD.

Figure 1

Demonstrates the expression of (A) TRAAK, (B) TREK-1 and (C) TASK-2 in non-human primate sperm (Macaca nemestrina). Columns 1, Rat brain extract; 2, native sperm. The asterisk (*) indicates protein bands at ~100 KD.

Figure 1

Demonstrates the expression of (A) TRAAK, (B) TREK-1 and (C) TASK-2 in non-human primate sperm (Macaca nemestrina). Columns 1, Rat brain extract; 2, native sperm. The asterisk (*) indicates protein bands at ~100 KD.

Figure 2

Illustrates the regional distributions of (A, a) TRAAK, (B, b) TREK-1 and (C, c) TASK-2 in non-human primate sperm (Macaca nemestrina). Sperm exposed to secondary antibody in the absence of exposure to primary antibodies directed against K_2P channel isoforms served as negative controls (D, d). Images with capital letters are light microscope images whereas images with lower case letters represent fluorescent images for each K_2P isoform. The horizontal bar indicates a distance of 10 μm.

Figure 2

Illustrates the regional distributions of (A, a) TRAAK, (B, b) TREK-1 and (C, c) TASK-2 in non-human primate sperm (Macaca nemestrina). Sperm exposed to secondary antibody in the absence of exposure to primary antibodies directed against K_2P channel isoforms served as negative controls (D, d). Images with capital letters are light microscope images whereas images with lower case letters represent fluorescent images for each K_2P isoform. The horizontal bar indicates a distance of 10 μm.

Figure 2

Illustrates the regional distributions of (A, a) TRAAK, (B, b) TREK-1 and (C, c) TASK-2 in non-human primate sperm (Macaca nemestrina). Sperm exposed to secondary antibody in the absence of exposure to primary antibodies directed against K_2P channel isoforms served as negative controls (D, d). Images with capital letters are light microscope images whereas images with lower case letters represent fluorescent images for each K_2P isoform. The horizontal bar indicates a distance of 10 μm.

Figure 2

Illustrates the regional distributions of (A, a) TRAAK, (B, b) TREK-1 and (C, c) TASK-2 in non-human primate sperm (Macaca nemestrina). Sperm exposed to secondary antibody in the absence of exposure to primary antibodies directed against K_2P channel isoforms served as negative controls (D, d). Images with capital letters are light microscope images whereas images with lower case letters represent fluorescent images for each K_2P isoform. The horizontal bar indicates a distance of 10 μm.