ATP increases head volume in capacitated human sperm via a purinergic channel.

Scanning ion-conductance microscopy allowed us to document an external Ca2+ dependent ATP driven volume increase (ATPVI) in capacitated human sperm heads. We examined the involvement of purinergic receptors (PRs) P2X2R and P2X4R in ATPVI using their co-agonists progesterone and Ivermectin (Iver), and Cu2+, which co-activates P2X2Rs and inhibits P2X4Rs. Iver enhanced ATPVI and Cu2+ and 5BDBD inhibited it, indicating P2X4Rs contributed to this response. Moreover, Cu2+ and 5BDBD inhibited the ATP-induced acrosome reaction (AR) which was enhanced by Iver. ATP increased the concentration of intracellular Ca2+ ([Ca2+]i) in >45% of individual sperm, most of which underwent AR monitored using FM4-64. Our findings suggest that human sperm P2X4R activation by ATP increases [Ca2+]i mainly due to Ca2+ influx which leads to a sperm head volume increase, likely involving acrosomal swelling, and resulting in AR.

K+ and Cl- channels and transporters in sperm function.

To succeed in fertilization, spermatozoa must decode environmental cues which require a set of ion channels. Recent findings have revealed that K(+) and Cl(-) channels participate in some of the main sperm functions. This work reviews the evidence indicating the involvement of K(+) and Cl(-) channels in motility, maturation, and the acrosome reaction, and the advancement in identifying their molecular identity and modes of regulation. Improving our insight on how these channels operate will strengthen our ability to surmount some infertility problems, improve animal breeding, preserve biodiversity, and develop selective and secure male contraceptives.

Sonographic anatomy of the neck: The suprahyoid region.

The suprahyoid region extends from the base of the skull to the hyoid bone and includes the pharyngeal, parapharyngeal, parotid, carotid, masticator, retropharyngeal, and perivertebral spaces, as well as the oral cavity. The areas that can be explored by ultrasound include the parotid, carotid, and masticator spaces; the oral cavity; the submandibular and sublingual spaces; the floor of the mouth; and the root of the tongue. The parotid space contains the parotid gland and the excretory duct of Steno, the facial nerve, the external carotid artery, the retromandibular vein, and the intraparotid lymph nodes. The carotid space in the suprahyoid region of the neck contains the internal carotid artery, the internal jugular vein, cranial nerves IX to XII, and the sympathetic plexus. Only some parts of the masticator space can be explored sonographically: these include the masseter muscle, the zygomatic arch and the outer cortex of the ramus of the mandible, and the suprazygomatic portion of the temporalis muscle. The submandibular space houses the submandibular gland, the submental and submandibular lymph nodes, and the anterior belly of digastric muscle. The facial artery and vein and the lower loop of the hypoglossal nerve all pass through the submandibular space. The sublingual space includes the sublingual gland, the deep portion of the submandibular gland and its main excretory duct, the hypoglossal nerve (cranial nerve XII), the lingual nerve (branch of the mandibular branch of trigeminal), and the glossopharyngeal nerve (IX cranial nerve), and the lingual artery and vein. The mylohyoid muscle forms the floor of the mouth. The deepest portion of the oral tongue, the root, consists of the genioglossus and geniohyoid muscles and includes the septum of the tongue. In this article we present the ultrasound features of the structures located in the suprahyoid region of the neck.

Cardiac cellular actions of hydrochlorothiazide.

In long term treatment, thiazide diuretics such as hydrochlorothiazide (HCTZ) lower blood pressure by decreasing peripheral resistance rather than by their diuretic effect. This action has been attributed to the opening of Ca2+-activated K+ channels in vascular smooth muscle cells. However, little is known about their cardiac cellular actions. Here we investigated the possible actions of HCTZ on action potential and contraction of rat ventricular muscle strips and on the ionic currents of isolated rat ventricular cardiomyocytes. HCTZ depressed ventricular contraction with an IC30 of 1.85 microM (60% decrease at 100 microM). Action potential duration at -60 mV and maximal rate of depolarization were, however, only slightly decreased by 12% and 22%, respectively, at 100 microM. At the single cell level, HCTZ (100 microM) depressed the fast Na+ current (INa) and the L-type Ca2+ current (ICaL) by 30% and 20%, respectively. The effects on ICaL were not voltage-or frequency-dependent. In cells intracellularly perfused with 50 microM cyclic adenosine, monophosphate HCTZ reduced ICaL by 33%. The transient (Ito), the delayed rectifier and the inward rectifier potassium currents were decreased by 20% at 100 microM HCTZ. The effects on Ito were voltage-dependent. In conclusion, HCTZ at high concentrations possesses a negative inotropic action that could be in part due to its blocking action on INa and ICaL. The actions of HCTZ on multiple cardiac ionic currents could explain its weak effect on action potential duration.

Factors affecting lipoprotein lipase in hypertensive patients.

Arterial hypertension is frequently associated with serum lipid abnormalities. Lipid metabolism can also be affected by antihypertensive treatment, possibly via an interference with lipoprotein lipase (LPL) activity. The aims of this study were to investigate the metabolic and hemodynamic factors that can interfere with plasma postheparin LPL activity in a sample of 13 patients with mild, uncomplicated arterial hypertension. The effects of vasodilator administration (prazosin and hydralazine) alone or in combination with a beta-blocker (propranolol) were also studied. A direct correlation between serum insulin levels and LPL activity was found during placebo treatment. This was confirmed by multiple regression analysis, which also showed a positive correlation of LPL activity with aortic flow velocity and plasma adrenaline (F significance = 0.0007, R2 = .905). Serum insulin was also directly correlated with cholesterol in high-density lipoproteins (HDLs) and in the HDL2 subfraction. A significant decrease in LPL activity was observed during the addition of propranolol to vasodilators as compared with vasodilators alone. A positive correlation was found between LPL and adrenaline changes induced by the combined treatment. These data suggest that LPL may play a role in the pathophysiologic connections between insulin action, the adrenergic nervous system (ANS), and lipid metabolism.