:: Asian Journal of Andrology ::

Studies on plasma endothelin changes in varicocele patients

Qing-Quan XU, Ji-Chuan ZHU, Hui JIANG, Xiao-Feng WANG, Shu-Kun HOU, Qing-Li LIU

Department of Urology, People's Hospital, Beijing Medical University, Beijing 100011, China

Asian J Androl 1999 Sep; 1: 159-160

Keywords: endothelin; varicocele; infertility

Abstract

Aim: To investigate the possible role endothelin may play in the pathogenesis of varicocele and varicocele-induced infertility. Methods: In varicocele patients, radioimmunoassay is used to determine the blood endothelin concentration in the spermatic vein and the antecubital vein separately. Results: The blood endothelin concentration of the spermatic vein (66.823.5 pg/mL) was significantly higher (P<0.05) than that of the antecubital vein (55.325.3 pg/mL). The endothelin concentration in the spermatic vein in Grade II varicocele patients was not significantly different from that in Grade III patients (P=0.87). Conclusion: The higher blood endothelin level in the spermatic vein may indicate the involvement of endothelin in the pathophysiology of varicocele and varicocele-induced infertility.

1 Introduction

Varicocele is a common etiologic factor of male infertility. The semen quality in men with varicocele is significantly lower that those in normal control subjects. The pathophysiology of varicocele-induced infertility remains unclear. In order to clarify the role played by endothelin in varicocele and varicocele-induced infertility, the authors determined the endothelin concentration in the spermatic vein and the antecubital vein separately by means of radioimmunoassay.

2 Materials and methods

2.1 Subjects

Twenty varicocele patients (Grade II, n=8; Grade III, n=12) with a mean age of 26.4 years (13-38 years) participated in the study. Ten were unmarried and the other 10 married. In the married cases, 5 were infertile.

2.2 Radioimmunoassay kit

Purchased from the Eastern Asia Immunology Technology Institute.

2.3 Procedure

Two mL of blood were aspirated separately from the antecubital vein and the spermatic vein and plasma was then prepared. The endothelin concentration was determined by a routine immunoassay method.

2.4 Statistical analysis

Data were presented as means and statistical analysis was performed using paired t test. Significance of differences was set at P<0.05.

3 Results

The blood endothelin concentration of the spermatic vein (66.823.5 pg/mL) was significantly higher (P<0.05) than that of the antecubital vein (55.325.3 pg/mL). The endothelin concentration in the spermatic vein in Grade II varicocele patients was not significantly different from that in Grade III patients (P=0.87).

4 Discussion

Varicocele is the most common cause of reversible male infertility. Varicocele is present in 10%-20% of all males, but is found in as many as 30%-40% of the patients visiting an infertility clinic^[1]. There are many hypotheses about the cause of infertility in varicocele patient, including hormone imbalance, oxygen lack caused by blood stasis in the spermatic vein, countercurrent of metabolic products from adrenal and renal veins, testicular hyperthermia, chromosome abnormality, etc. However, the precise pathogenesis of varicocele-induced infertility remains obscure.

Endothelins are a family of contractile polypeptides made up of 21 amino acids. They are the most powerful vasoconstrictors ever existed and may adjust the local vascular tension through paracrine and autocrine mechanisms^[2]. They have 3 kinds of isopeptides, the ET-1, ET-2, and ET-3^[3]. Endothelins and their receptors are found in human and animal testes. They can also adjust the testicular function through autocrine and paracrine mechanisms^[4,5]. It has been reported that there are massive immunoreactive endothelins in the human seminal fluid^[6]. The paper showed an abnormally high concentration of endothelin in the spermatic vein of varicocele patients, which might indicate the involvement of the substance in the pathophysiology of varicocele and varicocele-induced infertility.

References

[1] Honig SC, Thompson S, Lipshultz LI. Reassessment of male-factor infertility, including the varicocele, sperm penetration assay, semen analysis, and in vitro fertilization. Curr Opin Obstet Gynecol 1993; 5: 245-51.
[2] Yanagisawa M, Kurihara H, Kimura S, Tomobe Y, Kobayashi M, Mitsui Y, et al. A novel potent vasoconstractor peptide produced by vascular endothelial cells. Nature 1988; 332: 411-5.
[3] Inoue A, Yanagisawa M, Kimura S, Kasuya Y, Miyauchi T, Goto K, et al. The human endothelin family: three structurally and pharmacologically distinct isopeptides predicted by three separate genes. Proc Natl Acad Sci USA. 1989; 86: 2863-7.
[4] Maggi M, Barni T, Orlando C, Fantoni G, Finetti G, Vannelli GB, et al. Endothelin-1 and its receptors in human testis. J Androl 1995; 16: 213-24.
[5] Sakaguchi H, Kozuka M, Hirose S, Ito T, Hagiwara H. Properties and localization of endothelin-1 specific receptors in rat testicles. Am J Physiol 1992; 263 (1 Pt 2): 15-8.
[6] Casey ML, Byrd W, MacDonald PC. Massive immunoreactive endothelin in human seminal fluid. J Clin Endocrinol Metab 1992; 74: 223-5.

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Correspondence to Prof. Ji-Chuan ZHU, President of Society of Andrology, Chinese Medical Association.
Tel: +86-10-6831 4422, ext 4207 Fax: +86-21-6831 8386
E-mail: zhujc@yeah.net
Received 1999-09-08 Accepted 1999-09-16